Can we nest two OptionMenu widgets in tkinter?

If your mean is to create two OptionMenu and it will show the different value when select different value in the first dropdown menu.You can try this:

import tkinter as tkfrom tkinter import ttkfrom tkinter import *def func(selected_value): # the selected_value is the value you selected in the first drop down menu.    dropMenu2.set_menu(*optionList2.get(selected_value))root = tk.Tk()root.geometry('500x500')#Label to Continentlabel_1 = tk.Label(root, text="Select the Continent", font = (8), bg = '#ffe1c4')label_1.place(x = 120, y = 220)# Continent selection - drop downoptionList1 = ["-","Continent1", "Continent2","Continent3"]dropVar1 = StringVar()dropMenu1 = ttk.OptionMenu(root, dropVar1 , *optionList1,command=func) # bind a command for the first dropmenudropMenu1.place(x = 300, y = 220)#Label to Select Countrylabel_2 = tk.Label(root, text="Select the Country ", font = (8), bg = '#ffe1c4')label_2.place(x = 120, y = 250)# Country  name selection - drop downoptionList2 = { # when select different value,show the list.    "Continent1": ["Country_11", "Country_12"],    "Continent2": ["Country_21", "Country_22"],    "Continent3": ["Country_31", "Country_32"]}dropVar2 = StringVar()dropMenu2 = ttk.OptionMenu(root, dropVar2, "-")dropMenu2.place(x = 300, y = 250)root.mainloop()

Now it is:

When select another value:

(A suggestion:ttk.Combobox is prettier than OptionMenu,and using from tkinter import * is not a good practice.)

If you mean menu inside a menu then it is possible and very simple to do because the menu used in OptionMenu() is a tkinter Menu(), See the documentation of tkinter Menu.

We can access the Menu like so

Op = OptionMenu(root, var, 'Hello', 'HI', 'YOO')# Op_Menu is the Menu() class used for OptionMenuOp_Menu = Op['menu']

Here is a small example of nested menus in an option menu. When you select any of the countries inside any continent the text of optionmenu won't change so to fix that I used command argument and in each command argument of country I'm changing the value of the StringVar that is assigned to the optionmenu.

import tkinter as tkroot = tk.Tk()svar = tk.StringVar()svar.set('Antarctica')Op = tk.OptionMenu(root, svar, svar.get())OpMenu = Op['menu']Op.pack()Menu1 = tk.Menu(OpMenu)OpMenu.add_cascade(label='Africa', menu= Menu1)Menu1.add_command(label='Algeria', command=lambda: svar.set('Africa - Algeria'))Menu1.add_command(label='Benin', command=lambda: svar.set('Africa - Benin'))Menu2 = tk.Menu(Op['menu'])OpMenu.add_cascade(label='Asia', menu= Menu2)Menu2.add_command(label='China', command=lambda: svar.set('Asia - China'))Menu2.add_command(label='India', command=lambda: svar.set('Asia - India'))root.mainloop() 

Hope you find this helpful.