In 2000, Lennon contributed vocals to Del tha Funkee Homosapien (a single stanza on the Deltron 3030 track "Memory Loss"), Handsome Boy Modeling School and Jurassic 5. In 2001 on national television, Lennon performed several classics by the Beatles, "This Boy", "Across the Universe" and "Julia" alongside Robert Schwartzman, Rufus Wainwright and Moby for Come Together: A Night for John Lennon's Words and Music. In the following years Lennon faded out of the spotlight to focus more on his role as a producer.
While reestablishing himself as a solo artist, Lennon continued his work as a session musician and producer, lending his talent to the likes of Dopo Yume, Albert Hammond, Jr. (of the Strokes) and model/singer Irina Lăzăreanu. Lennon first appeared on the Soulfly album Primitive, released in 2000, while in October 2007, Lennon joined Mark Ronson in the BBC Electric Proms where he sang "Sail on, Sailor", as well as "We Can Work It Out" alongside Daniel Merriweather, and Tawiah. The year prior, he wrote and directed his first film, Friendly Fire, starring Carrie Fisher, Lindsay Lohan and others. His eponymous second studio LP served as the film's soundtrack as well.