The Gossip Girl alum and Williams covered the Fleetwood Mac classic in a dreamy duet with Maxwell Drummey on percussion.
The performance was posted just a day before news broke that Christine McVie will rejoin Fleetwood Mac. The band will embark on their reunion tour, On With the Show, on September 30.
Meester has pursued music several different times in the past. The actress has recorded several singles, and also sang in the 2010 movie Country Strong. She and actor Adam Brody married earlier this year.
Swim Week Miami Beach 2014 [PHOTOS]