"1 Thing" received acclaim from music critics. In its review of
Touch,
Rolling Stone named the song "an early front-runner for
song-of-the-summer status", also ranking it the number one single of 2005.
Pitchfork stated that Harrison "knows something about horns, big glorious ascending heavenly anthemic horns" and "drums, huge sweaty riotous back-and-forth second-line old-school
Clyde Stubblefield drums."
AllMusic described "1 Thing" as being "just as exciting" as "Oh, Calcutta!" for how it "[flails] all over the place with unbound joy". The song received second place behind
Kanye West and
Jamie Foxx's "
Gold Digger" on the 2005
Village Voice Pazz & Jop list, a survey of several hundred music critics conducted by
Robert Christgau.
Blender ranked "1 Thing" number 191 on its list of "The 500 Greatest Songs Since You Were Born". It praised the song's "cascading drums...and Amerie's frantic, top-of-her-range vocals". Calling it "a pretty fucking smart move to wrap perfect
pop around a question that stays open all night",
Pitchfork listed the song as the second best single of 2005, behind
Antony and the Johnsons' "
Hope There's Someone". The song was ranked 32nd on
Pitchfork's top 500 songs of the 2000s, and the publication included "1 Thing" in its collection of
The Pitchfork 500. Christgau named it the 25th best song of the 2000s.
Björk also dubbed it the "Best! Song! Ever!" The song received a nomination for
Best Female R&B Vocal Performance at the
48th Annual Grammy Awards, but lost to
Mariah Carey's "
We Belong Together". ==Commercial performance==