How do I bind the enter key to a function in tkinter?

Try running the following program. You just have to be sure your window has the focus when you hit Return–to ensure that it does, first click the button a couple of times until you see some output, then without clicking anywhere else hit Return.

import tkinter as tk

root = tk.Tk()
root.geometry("300x200")

def func(event):
    print("You hit return.")
root.bind('<Return>', func)

def onclick():
    print("You clicked the button")

button = tk.Button(root, text="click me", command=onclick)
button.pack()

root.mainloop()

Then you just have tweak things a little when making both the button click and hitting Return call the same function–because the command function needs to be a function that takes no arguments, whereas the bind function needs to be a function that takes one argument(the event object):

import tkinter as tk

root = tk.Tk()
root.geometry("300x200")

def func(event):
    print("You hit return.")

def onclick(event=None):
    print("You clicked the button")

root.bind('<Return>', onclick)

button = tk.Button(root, text="click me", command=onclick)
button.pack()

root.mainloop()

Or, you can just forgo using the button’s command argument and instead use bind() to attach the onclick function to the button, which means the function needs to take one argument–just like with Return:

import tkinter as tk

root = tk.Tk()
root.geometry("300x200")

def func(event):
    print("You hit return.")

def onclick(event):
    print("You clicked the button")

root.bind('<Return>', onclick)

button = tk.Button(root, text="click me")
button.bind('<Button-1>', onclick)
button.pack()

root.mainloop()

Here it is in a class setting:

import tkinter as tk

class Application(tk.Frame):
    def __init__(self):
        self.root = tk.Tk()
        self.root.geometry("300x200")

        tk.Frame.__init__(self, self.root)
        self.create_widgets()

    def create_widgets(self):
        self.root.bind('<Return>', self.parse)
        self.grid()

        self.submit = tk.Button(self, text="Submit")
        self.submit.bind('<Button-1>', self.parse)
        self.submit.grid()

    def parse(self, event):
        print("You clicked?")

    def start(self):
        self.root.mainloop()


Application().start()