It's possible!
If you check out the button documentation, you can use an image to display on the button.
For example:
from tkinter import *
root = Tk()
button = Button(root, text="Click me!")
img = PhotoImage(file="C:/path to image/example.gif") # make sure to add "/" not "\"
button.config(image=img)
button.pack() # Displaying the button
root.mainloop()
This is a simplified example for adding an image to a button widget, you can make many more cool things with the button widget.