The video features DeGeneres playing a piano and singing, "Michelle Obama has a new book."
The former first lady quickly steps into the shot and takes a seat next to the TV personality, before correcting DeGeneres by singing, "It's actually a journal."
The new project, Becoming: A Guided Journal for Discovering Your Voice, a spinoff of sorts of Obama's 2018 memoir, was released earlier this week.
"The purpose of the journal is to write down your own story of becoming," Obama explains as DeGeneres continues to play the piano. "To chronicle your memories, your thoughts, your ideas, your impressions…because every story matters. Even yours, Ellen."
The women break into a duet from there, both of them singing, "What is my story?" and Obama closing out the clip by singing, "Who are you becoming?"
"Last night, I dropped by my friend Ellen's house for a little duet," Obama captioned the post.
DeGeneres shared the same clip, quipping, "We’re thinking about putting out a whole album."