Adele's hit album 30 and The Weeknd's reflective single Save Your Tears were the world's best-selling records of 2021, according to music industry data.
Adele's highly-anticipated fourth album sold more than five million copies in just two months, said the IFPI.
It was the biggest-selling record on vinyl and CD, the industry body added.
Meanwhile, The Weeknd's moody retro-pop ballad topped the charts in 18 countries, and was streamed 2.15 billion times.
It was the second year running that the Canadian star delivered the world's most popular song.
Last year's chart-topper, Blinding Lights, made the top 10 for a second time in 2021, at number seven.
Canada also claimed the second spot on the IFPI's list of best-selling singles, thanks to Justin Bieber's collaboration with Australian singer-songwriter The Kid Laroi.
Their hit, Stay, was the only other song to top two billion streams in 2021.
Dua Lipa came close, though, with her disco-throwback anthem Levitating attracting 1.88 billion worldwide plays to take third place.
The IFPI's annual chart of the year tallies downloads, streams and physical purchases to compile the planet's biggest hits.
The methodology tends to favour records from the start of the year, as they have more time to accumulate sales - and it's no surprise that all of the top 10 singles were released before June 2021.
Adele's album bucks that trend. It beat the competition after just six weeks of release, a stark illustration of the star's pulling power after a six-year hiatus.