For their first turn on the SNL stage, they dressed up in sparkling silver suits for "Nothing Breaks Like a Heart," in which Cyrus holds tight to her country roots and Ronson picks up an acoustic guitar.
With a string quartet and footage of a car chase straight out of the song's music video -- including its full-throttle, destructive finish -- rolling as their backdrop, Cyrus crooned her way through the moody ballad as Ronson plucked out the dramatic tune by her side.
READ MOREMiley Cyrus & Mark Ronson Surprise London Crowd with Acoustic 'Nothing Breaks Like a Heart' Performance: Watch
Cyrus then traded in her platinum look for seasonal sequins, wearing a red, floral sequined cocktail dress that matched the poinsettias crowding the floor of the SNLset for her cover of "Happy Xmas (War Is Over)."
After an introduction from Pete Davidson, Sean Ono Lennon joined Cyrus, Ronson and their band for the performance of their take on the nostalgic 1971 single, shredding and offering back-up vocals while Cyrus belted the song's iconic chorus at the top of her voice.