Add VBA Code to an Option button dynamically

You’re correct — UserForm OptionButtons do not have .OnAction.
That property only exists for Worksheet controls (Form Controls).
UserForm controls use class modules and events, not .OnAction.

Below is a working, VBA solution (I hope so 😊) you can paste directly into your project.
It dynamically creates OptionButtons on a UserForm and captures which button was clicked, returning the Caption of the selected button.

Create Class Module: clsOptButton

Insert → Class Module
Rename it exactly:

clsOptButton

Paste this code:

Option Explicit

Public WithEvents Opt As MSForms.OptionButton   ' dynamic OptionButton with events

Private Sub Opt_Click()
    ' When clicked, send the caption back to the UserForm
    uFrmChoice.SelectedOption = Opt.Caption
End Sub

UserForm Code (uFrmChoice)

Open your UserForm → paste this code into the form.

This version creates dynamic buttons, aligns them, and stores the selected option.

Option Explicit

Public SelectedOption As String      ' holds the chosen option
Private OptHandlers As Collection    ' stores event handler objects

Private Sub UserForm_Initialize()
    Dim i As Long, x As Long
    Dim objOptBtn As MSForms.OptionButton
    Dim handler As clsOptButton
    Dim topPos As Long
    
    x = 10  ' number of options (example) — replace with your own dynamic count

    Set OptHandlers = New Collection
    topPos = 20
    
    For i = 1 To x
    
        ' Create the OptionButton
        Set objOptBtn = Me.Controls.Add("Forms.OptionButton.1", "objOptBtn" & i, True)

        With objOptBtn
            .Caption = "Option " & i
            .Left = 20
            .Top = topPos
            .Width = 150
            .Height = 18
        End With
        
        topPos = topPos + 22
        
        ' Create event handler and bind the control to it
        Set handler = New clsOptButton
        Set handler.Opt = objOptBtn
        
        ' Must store handler to keep events alive
        OptHandlers.Add handler
    Next i
End Sub

Show the form from anywhere

In a standard module:

Sub TestDynamicOptions()
    uFrmChoice.SelectedOption = ""      ' reset
    uFrmChoice.Show                     ' show UserForm
    
    If uFrmChoice.SelectedOption <> "" Then
        MsgBox "You selected: " & uFrmChoice.SelectedOption
    Else
        MsgBox "No option selected."
    End If
End Sub

You can copy all 3 code pieces exactly and it will run immediately....i hope so 🙂...the codes are not testet, please backup your file first.

Hope this helps you.