[6] After he signed with Atlantic Records in 2009, he composed (as part of production group the Smeezingtons) and sang guest vocals on the debut singles of American rappers B.o.B ("Nothin' on You") (2009) and Travie McCoy ("Billionaire") (2010).

Its singles "Just the Way You Are" and "Grenade" topped the charts in the US, Australia, Canada, New Zealand and the UK, and have been certified 13 times platinum and diamond, respectively, by the RIAA.

In 2011, Mars recorded "It Will Rain" for the soundtrack of The Twilight Saga: Breaking Dawn – Part 1 and appeared on a number of collaborative singles, including "Young, Wild & Free" by Snoop Dogg and Wiz Khalifa, which was certified six times platinum by the RIAA.

In 2014, Mars provided vocals on Mark Ronson's "Uptown Funk", which topped the US, Australia, Canada, New Zealand and UK music charts.

In 2018, Gucci Mane, Mars and Kodak Black released the single "Wake Up in the Sky", which was certified six times platinum by the RIAA.

Two of its singles, "Leave the Door Open" and "Smokin out the Window", both reached the top ten on several charts with the former peaking at number one in the United States and New Zealand.