Schumer posted a video of her as a kid singing "Like A Prayer."
Schumer will appear at Madonna's Madison Square Garden shows Sept. 16 and 17, as well as at Brooklyn's Barclays Center on Sept. 19.
The "Ghosttown" singer is the queen of cameos lately. She debuted her "Bitch I'm Madonna" music video yesterday and featured split-second cameos from Miley Cyrus, Beyonce, Katy Perry, Kanye West, Diplo, Rita Ora and more. Looks like she can add Schumer to the lengthy "Rebel Heart" list.