Which Mariah Carey song did Billboard list as the song of the 2000s decade?

Billboard listed Mariah Carey’s “We Belong Together” as the song of the 2000s decade.

Released in 2005 as the second single from The Emancipation of Mimi, the song became a major comeback for Carey after a comparatively difficult period earlier in the decade. Its restrained piano arrangement, conversational lyrics, and R&B production helped it connect with both pop and urban radio audiences.

“We Belong Together” reached number one on the Billboard Hot 100 and stayed there for 14 nonconsecutive weeks. It also became one of Carey’s most important career records, reinforcing her status as a dominant singles artist and songwriter.

The decade designation refers to Billboard’s decade-end Hot 100 ranking, not simply the song that sold the most copies or won the most awards. The song was ranked first for the 2000–2009 period, ahead of other major hits from the decade. It is also commonly confused with “One Sweet Day,” which Billboard identified as the most successful song of the 1990s.