Much harder to do that I'd envisaged. I found an version here by keepitcool that avoids the dreaded Sendkeys

Run this from a regular module.

Updated as initial post missed the Private Function Declarations - poor copy and paste job by yours truly

Private Declare Function GetWindow _
Lib "user32" ( _
ByVal hWnd As Long, _
ByVal wCmd As Long) As Long
Private Declare Function FindWindow _
Lib "user32" Alias "FindWindowA" ( _
ByVal lpClassName As String, _
ByVal lpWindowName As String) As Long
Private Declare Function FindWindowEx _
Lib "user32" Alias "FindWindowExA" _
(ByVal hWnd1 As Long, ByVal hWnd2 As Long, _
ByVal lpsz1 As String, _
ByVal lpsz2 As String) As Long
Private Declare Function GetKeyboardState _
Lib "user32" (pbKeyState As Byte) As Long
Private Declare Function SetKeyboardState _
Lib "user32" (lppbKeyState As Byte) As Long
Private Declare Function PostMessage _
Lib "user32" Alias "PostMessageA" ( _
ByVal hWnd As Long, ByVal wMsg As Long, _
ByVal wParam As Long, ByVal lParam As Long _
) As Long




Private Const WM_KEYDOWN As Long = &H100
Private Const KEYSTATE_KEYDOWN As Long = &H80




Private savState(0 To 255) As Byte




Sub ClearImmediateWindow()
'Adapted  by   keepITcool
'Original from Jamie Collins fka "OneDayWhen"
'http://www.dicks-blog.com/excel/2004/06/clear_the_immed.html




Dim hPane As Long
Dim tmpState(0 To 255) As Byte




hPane = GetImmHandle
If hPane = 0 Then MsgBox "Immediate Window not found."
If hPane < 1 Then Exit Sub




'Save the keyboardstate
GetKeyboardState savState(0)




'Sink the CTRL (note we work with the empty tmpState)
tmpState(vbKeyControl) = KEYSTATE_KEYDOWN
SetKeyboardState tmpState(0)
'Send CTRL+End
PostMessage hPane, WM_KEYDOWN, vbKeyEnd, 0&
'Sink the SHIFT
tmpState(vbKeyShift) = KEYSTATE_KEYDOWN
SetKeyboardState tmpState(0)
'Send CTRLSHIFT+Home and CTRLSHIFT+BackSpace
PostMessage hPane, WM_KEYDOWN, vbKeyHome, 0&
PostMessage hPane, WM_KEYDOWN, vbKeyBack, 0&




'Schedule cleanup code to run
Application.OnTime Now + TimeSerial(0, 0, 0), "DoCleanUp"




End Sub




Sub DoCleanUp()
' Restore keyboard state
SetKeyboardState savState(0)
End Sub




Function GetImmHandle() As Long
'This function finds the Immediate Pane and returns a handle.
'Docked or MDI, Desked or Floating, Visible or Hidden




Dim oWnd As Object, bDock As Boolean, bShow As Boolean
Dim sMain$, sDock$, sPane$
Dim lMain&, lDock&, lPane&




On Error Resume Next
sMain = Application.VBE.MainWindow.Caption
If Err <> 0 Then
MsgBox "No Access to Visual Basic Project"
GetImmHandle = -1
Exit Function
' Excel2003: Registry Editor (Regedit.exe)
'    HKLM\SOFTWARE\Microsoft\Office\11.0\Excel\Security
'    Change or add a DWORD called 'AccessVBOM', set to 1
' Excel2002: Tools/Macro/Security
'    Tab 'Trusted Sources', Check 'Trust access..'
End If




For Each oWnd In Application.VBE.Windows
If oWnd.Type = 5 Then
bShow = oWnd.Visible
sPane = oWnd.Caption
If Not oWnd.LinkedWindowFrame Is Nothing Then
bDock = True
sDock = oWnd.LinkedWindowFrame.Caption
End If
Exit For
End If
Next
lMain = FindWindow("wndclass_desked_gsk", sMain)
If bDock Then
'Docked within the VBE
lPane = FindWindowEx(lMain, 0&, "VbaWindow", sPane)
If lPane = 0 Then
'Floating Pane.. which MAY have it's own frame
lDock = FindWindow("VbFloatingPalette", vbNullString)
lPane = FindWindowEx(lDock, 0&, "VbaWindow", sPane)
While lDock > 0 And lPane = 0
lDock = GetWindow(lDock, 2) 'GW_HWNDNEXT = 2
lPane = FindWindowEx(lDock, 0&, "VbaWindow", sPane)
Wend
End If
ElseIf bShow Then
lDock = FindWindowEx(lMain, 0&, "MDIClient", _
vbNullString)
lDock = FindWindowEx(lDock, 0&, "DockingView", _
vbNullString)
lPane = FindWindowEx(lDock, 0&, "VbaWindow", sPane)
Else
lPane = FindWindowEx(lMain, 0&, "VbaWindow", sPane)
End If




GetImmHandle = lPane




End Function

Below is a solution from here

Sub stance()
Dim x As Long


For x = 1 To 10
Debug.Print x
Next


Debug.Print Now
Application.SendKeys "^g ^a {DEL}"
End Sub

SendKeys is straight, but you may dislike it (e.g. it opens the Immediate window if it was closed, and moves the focus).

The WinAPI + VBE way is really elaborate, but you may wish not to grant VBA access to VBE (might even be your company group policy not to).

Instead of clearing you can flush its content (or part of it...) away with blanks:

Debug.Print String(65535, vbCr)

Unfortunately, this only works if the caret position is at the end of the Immediate window (string is inserted, not appended). If you only post content via Debug.Print and don't use the window interactively, this will do the job. If you actively use the window and occasionally navigate to within the content, this does not help a lot.

After some experimenting, I made some mods to mehow's code as follows:

1. Trap errors (the original code is falling over due to not setting a reference to "VBE", which I also changed to myVBE for clarity)
2. Set the Immediate window to visible (just in case!)
3. Commented out the line to return the focus to the original window as it's this line that causes the code window contents to be deleted on machines where timing issues occur (I verified this with PowerPoint 2013 x32 on Win 7 x64). It seems the focus is switching back before SendKeys has completed, even with Wait set to True!
4. Change the wait state on SendKeys as it doesn't seem to be adhered to on my test environment.

I also noted that the project must have trust for the VBA project object model enabled.

' DEPENDENCIES
' 1. Add reference:
' Tools > References > Microsoft Visual Basic for Applications Extensibility 5.3
' 2. Enable VBA project access:
' Backstage / Options / Trust Centre / Trust Center Settings / Trust access to the VBA project object model


Public Function ClearImmediateWindow()
On Error GoTo ErrorHandler
Dim myVBE As VBE
Dim winImm As VBIDE.Window
Dim winActive As VBIDE.Window


Set myVBE = Application.VBE
Set winActive = myVBE.ActiveWindow
Set winImm = myVBE.Windows("Immediate")


' Make sure the Immediate window is visible
winImm.Visible = True


' Switch the focus to the Immediate window
winImm.SetFocus


' Send the key sequence to select the window contents and delete it:
' Ctrl+Home to move cursor to the top then Ctrl+Shift+End to move while
' selecting to the end then Delete
SendKeys "^{Home}", False
SendKeys "^+{End}", False
SendKeys "{Del}", False


' Return the focus to the user's original window
' (comment out next line if your code disappears instead!)
'winActive.SetFocus


' Release object variables memory
Set myVBE = Nothing
Set winImm = Nothing
Set winActive = Nothing


' Avoid the error handler and exit this procedure
Exit Function


ErrorHandler:
MsgBox "Error " & Err.Number & vbCrLf & vbCrLf & Err.Description, _
vbCritical + vbOKOnly, "There was an unexpected error."
Resume Next
End Function

or even more simple

Sub clearDebugConsole()
For i = 0 To 100
Debug.Print ""
Next i
End Sub

Here is a combination of ideas (tested with excel vba 2007) :

' * (this can replace your day to day calling to debug)

Public Sub MyDebug(sPrintStr As String, Optional bClear As Boolean = False)
If bClear = True Then
Application.SendKeys "^g^{END}", True


DoEvents '  !!! DoEvents is VERY IMPORTANT here !!!


Debug.Print String(30, vbCrLf)
End If


Debug.Print sPrintStr
End Sub

I do not like deleting the Immediate content (fear of deleting the code by accident, so the above is a hack on some of the code you all wrote.

This handles the problem Akos Groller writes about above: "Unfortunately, this only works if the caret position is at the end of the Immediate window"

The code opens the Immediate window (or puts the focus on it), sends a CTRL+END, followed by a flood of newlines, so the previous debug content is not in sight.

Please note, that DoEvents is crucial, otherwise the logic would fail (the caret position would not move in time to the end of the Immediate window).

Sub ClearImmediateWindow()
SendKeys "^{g}", False
DoEvents
SendKeys "^{Home}", False
SendKeys "^+{End}", False
SendKeys "{Del}", False
SendKeys "{F7}", False
End Sub

I had the same problem. Here is how I resolved the issue with help from the Microsoft link: https://msdn.microsoft.com/en-us/library/office/gg278655.aspx

Sub clearOutputWindow()
Application.SendKeys "^g ^a"
Application.SendKeys "^g ^x"
End Sub

I'm in favor of not ever depending on the shortcut keys, as it may work in some languages but not all of them... Here's my humble contribution:

Public Sub CLEAR_IMMEDIATE_WINDOW()
'by Fernando Fernandes
'YouTube: Expresso Excel
'Language: Portuguese/Brazil
Debug.Print VBA.String(200, vbNewLine)
End Sub

For cleaning Immediate window I use (VBA Excel 2016) next function:

Private Sub ClrImmediate()
With Application.VBE.Windows("Immediate")
.SetFocus
Application.SendKeys "^g", True
Application.SendKeys "^a", True
Application.SendKeys "{DEL}", True
End With
End Sub

But direct call of ClrImmediate() like this:

Sub ShowCommandBarNames()
ClrImmediate
'--   DoEvents
Debug.Print "next..."
End Sub

works only if i put the breakpoint on Debug.Print, otherwise the clearing will be done after execution of ShowCommandBarNames() - NOT before Debug.Print. Unfortunately, call of DoEvents() did not help me... And no matter: TRUE or FALSE is set for SendKeys.

To solve this I use next couple of calls:

Sub ShowCommandBarNames()
'--    ClrImmediate
Debug.Print "next..."
End Sub


Sub start_ShowCommandBarNames()
ClrImmediate
Application.OnTime Now + TimeSerial(0, 0, 1), "ShowCommandBarNames"
End Sub

It seems to me that using Application.OnTime might be very useful in programming for VBA IDE. In this case it's can be used even TimeSerial(0, 0, 0).

Marked answer does not work if triggered via button in worksheet. It opens Go To excel dialog box as CTRL+G is shortcut for. You have to SetFocus on Immediate Window before. You may need also DoEvent if you want to Debug.Print right after clearing.

Application.VBE.Windows("Immediate").SetFocus
Application.SendKeys "^g ^a {DEL}"
DoEvents

For completeness, as @Austin D noticed:

For those wondering, the shortcut keys are Ctrl+G (to activate the Immediate window), then Ctrl+A (to select everything), then Del (to clear it).

I tested this code based on all the comments above. Seems to work flawlessly. Comments?

Sub ResetImmediate()
Debug.Print String(5, "*") & " Hi there mom. " & String(5, "*") & vbTab & "Smile"
Application.VBE.Windows("Immediate").SetFocus
Application.SendKeys "^g ^a {DEL} {HOME}"
DoEvents
Debug.Print "Bye Mom!"
End Sub

Previously used the Debug.Print String(200, chr(10)) which takes advantage of the Buffer overflow limit of 200 lines. Didn't like this method much but it works.

Just checked in Excel 2016 and this piece of code worked for me:

Sub ImmediateClear()
Application.VBE.Windows("Immediate").SetFocus
Application.SendKeys "^{END} ^+{HOME}{DEL}"
End Sub

If you happen to be using Autohotkey here's the script I use.

The key command is Ctrl+Delete. It only works if the VBE is active.
When pressed it will clear the immediate window and then activate the code editor, via F7.

I tend to want to clear the immediate when while I'm coding so now I can just hit Ctrl-Delete and keep coding. 👍

#IfWinActive, ahk_class wndclass_desked_gsk


^Delete:: clearImmediateWindow()


#If


clearImmediateWindow() {
Send, ^g
Send, ^a
Send, {Delete}
Send, {F7}
}

• No SendKeys?
• No VBA Extensibility?
• No 3rd Party Executables?
• No problem!

A Windows API Solution

Option Explicit


Private Declare PtrSafe _
Function FindWindowA Lib "user32" ( _
ByVal lpClassName As String, _
ByVal lpWindowName As String _
) As LongPtr
Private Declare PtrSafe _
Function FindWindowExA Lib "user32" ( _
ByVal hWnd1 As LongPtr, _
ByVal hWnd2 As LongPtr, _
ByVal lpsz1 As String, _
ByVal lpsz2 As String _
) As LongPtr
Private Declare PtrSafe _
Function PostMessageA Lib "user32" ( _
ByVal hwnd As LongPtr, _
ByVal wMsg As Long, _
ByVal wParam As LongPtr, _
ByVal lParam As LongPtr _
) As Long
Private Declare PtrSafe _
Sub keybd_event Lib "user32" ( _
ByVal bVk As Byte, _
ByVal bScan As Byte, _
ByVal dwFlags As Long, _
ByVal dwExtraInfo As LongPtr)


Private Const WM_ACTIVATE As Long = &H6
Private Const KEYEVENTF_KEYUP = &H2
Private Const VK_CONTROL = &H11


Sub ClearImmediateWindow()


Dim hwndVBE As LongPtr
Dim hwndImmediate As LongPtr
    

hwndVBE = FindWindowA("wndclass_desked_gsk", vbNullString)
hwndImmediate = FindWindowExA(hwndVBE, ByVal 0&, "VbaWindow", "Immediate")
PostMessageA hwndImmediate, WM_ACTIVATE, 1, 0&
    

keybd_event VK_CONTROL, 0, 0, 0
keybd_event vbKeyA, 0, 0, 0
keybd_event vbKeyA, 0, KEYEVENTF_KEYUP, 0
keybd_event VK_CONTROL, 0, KEYEVENTF_KEYUP, 0
    

keybd_event vbKeyDelete, 0, 0, 0
keybd_event vbKeyDelete, 0, KEYEVENTF_KEYUP, 0
    

End Sub

Thanks ProfoundlyOblivious,

No SendKeys, check
No VBA Extensibility, check
No 3rd Party Executables, check
One minor problem:

Localised Office versions use another caption for the immediate window. In Dutch it is named "Direct".
I have added one line to get the localised caption in case FindWindowExA fails. For those who use both the English and Dutch version of MS-Office.

+1 for you for doing most of the work!

Option Explicit


Private Declare PtrSafe Function FindWindowA Lib "user32" (ByVal lpClassName As String, ByVal lpWindowName As String) As LongPtr
Private Declare PtrSafe Function FindWindowExA Lib "user32" (ByVal hWnd1 As LongPtr, ByVal hWnd2 As LongPtr, ByVal lpsz1 As String, ByVal lpsz2 As String) As LongPtr
Private Declare PtrSafe Function PostMessageA Lib "user32" (ByVal hwnd As LongPtr, ByVal wMsg As Long, ByVal wParam As LongPtr, ByVal lParam As LongPtr) As Long
Private Declare PtrSafe Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Long, ByVal dwExtraInfo As LongPtr)


Private Const WM_ACTIVATE As Long = &H6
Private Const KEYEVENTF_KEYUP = &H2
Private Const VK_CONTROL = &H11


Public Sub ClearImmediateWindow()
Dim hwndVBE As LongPtr
Dim hwndImmediate As LongPtr
    

hwndVBE = FindWindowA("wndclass_desked_gsk", vbNullString)
hwndImmediate = FindWindowExA(hwndVBE, ByVal 0&, "VbaWindow", "Immediate") ' English caption
If hwndImmediate = 0 Then hwndImmediate = FindWindowExA(hwndVBE, ByVal 0&, "VbaWindow", "Direct") ' Dutch caption
PostMessageA hwndImmediate, WM_ACTIVATE, 1, 0&
    

keybd_event VK_CONTROL, 0, 0, 0
keybd_event vbKeyA, 0, 0, 0
keybd_event vbKeyA, 0, KEYEVENTF_KEYUP, 0
keybd_event VK_CONTROL, 0, KEYEVENTF_KEYUP, 0
   

keybd_event vbKeyDelete, 0, 0, 0
keybd_event vbKeyDelete, 0, KEYEVENTF_KEYUP, 0
End Sub

All of the solutions posted above have problems when the ClearImmediate function is called from a higher level Subroutine. For instance the following will usually end up with an EMPTY immediate window !

sub HigherLevel
debug.print "this message should disappear in 1 second"
call AnyOfAboveSolutions
debug.print "This message should appear in the immediate window"
End sub

But after many years I finally found a solution that works. First install the following to your VBA project.

    Option Explicit
Const Source = "c:\users\rdbmdl\"
Declare Function GetCurrentProcessId Lib "kernel32" () As Long
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)


Sub cls() ' also known as ClearScreen and ClearImmediateWindow
' see https://www.experts-exchange.com/questions/29228246/Vba-subroutines-to-clear-the-IDE-immediate-window-do-not-always-work.html


' the Cls routine Clears the immediate window during debugging.
' To install it you must create c:\users\rdbmdl\Vbaf5.vbs.
' if invoked from a runtime environment  ClearScreen will become disabled.


Dim safe As Single, ap As Object
Static Initialized As Boolean, Disabled As Boolean
If Not Initialized Then
Initialized = True
If Dir(Source & "vbaf5.vbs") = "" Then
MsgBox "Please install VbaF5.vbs"
Disabled = True
End If
End If
If Disabled Then Exit Sub
safe = VBA.DateTime.Timer
Shell Replace("wscript c:\users\rdbMdl\vbaf5.vbs ""%1""", "%1", GetCurrentProcessId), 1
Stop ' in a runtime environment Stop is ignored and ClearScreen gets disabled
' the Stop CANNOT be replaced with a Sleep. Things get very weird vba code that calls Cls gets a few bytes deleted.
If VBA.DateTime.Timer - safe < 0.01 Then
Disabled = True
End If
End Sub

Then install the following to C:\users\rdbmdl\vbaF5.vbs

' see https://www.experts-exchange.com/questions/29228246/Vba-subroutines-to-clear-the-IDE-immediate-window-do-not-always-work.html
Dim objServices, objProcessSet, process, desired
desired = "^g^a {DEL} {HOME}"
desired = desired & "{F7}^+{F2}{RIGHT}+{RIGHT}"
desired = desired & "{F5}"


Set objShell = wscript.CreateObject("WScript.Shell")
Set objargsinall = wscript.Arguments'
Set objServices = GetObject("winmgmts:\\.\root\CIMV2")
Set objProcessSet = objServices.ExecQuery("SELECT ProcessID FROM Win32_Process WHERE ProcessID =" & objargsinall(0), , 48)
   

For Each process In objProcessSet
objShell.AppActivate (process.ProcessID)
objShell.SendKeys desired
Next
' see https://www.experts-exchange.com/questions/29228246/Vba-subroutines-to-clear-the-IDE-immediate-window-do-not-always-work.html

My 11/17/2021 answer used vbscript and was fairly complicated.
The following is MUCH simpler and is entirely VBA. 95% of the time ClearStop is the best solution, but ClearGo is useful if you are using debug.print to help measure resource consumption in long running programs.

Declare Function GetKeyState Lib "user32" (ByVal nVirtKey As Long) As Integer
Sub ClearStop()
Application.SendKeys "^g^a^{DEL}"
Stop
End Sub
Sub ClearGo()
Application.SendKeys "^g^a^{DEL}" & IIf(GetKeyState(&H10) < 0, "", "{F5}")   'Shift key: see https://www.experts-exchange.com/questions/29228246/Vba-subroutines-to-clear-the-IDE-immediate-window-do-not-always-work.html
Stop
End Sub

I'm using this short code:

Sub clearDebug()
SendKeys "^g^a{DEL}"
End Sub

Problems to solve:

1. Clear the immediate window
2. After clearing the immediate window, further Debug.Print statements don't work
3. SendKeys sometimes Toggles NumLock (Microsoft Bug)

Option Explicit
Private Declare PtrSafe Function GetKeyState Lib "user32" (ByVal nVirtKey As Long) As Integer


Public Sub TestClearImmediateWindow()
Dim x As Integer
    

For x = 1 To 10
Debug.Print String(20, Chr(64 + x))
Next x
ClearImmediateWindow
Call Application.OnTime(DateAdd("s", 1, Now), "DoNextThing")
End Sub
Private Sub ClearImmediateWindow()
Const NUMLOCKKEYCODE = 144
Dim NumLockState As Integer
    

NumLockState = GetKeyState(NUMLOCKKEYCODE)
Call Application.SendKeys("^g^a{DEL}{F7}", True) ' Because of a bug, this line sometimes toggles NumLock
If NumLockState <> GetKeyState(NUMLOCKKEYCODE) Then Call Application.SendKeys("{NUMLOCK}", True)
End Sub
Private Sub DoNextThing()
Dim x As Integer
    

For x = 1 To 10
Debug.Print String(20, Chr(74 + x))
Next x
End Sub

Application.VBE.Windows("Immediate").SetFocus
Application.SendKeys "^a", True
Application.SendKeys "{DEL}", True

If error : Programmatic Access To Visual Basic Project Is Not Trusted