Billboard magazine says the boy band led by Justin Timberlake had the decade's best-selling album with "No Strings Attached," which sold more than 10 million copies.
The most popular song of the decade was Mariah Carey's ballad "We Belong Together."
Eminem was named the top artist of the decade, while Nickelback was named top group.
For 2009, Taylor Swift had the best-selling album with "Fearless," while the Black Eyed Peas' "Boom Boom Pow" was top song.
Billboard released those chart-toppers plus others for the decade and 2009 on its Web site on Friday.