"Ain't No Other Man" in written the key of F minor, with a moderate fast tempo of 132 beats per minute. Aguilera's vocal range on the track spans from A3 to C5. Dorian Lyskey of "The Guardian" noted that the beats of the song are "brassy" and have the same "aerobic oomph" as Beyoncé's "Crazy in Love", while Jody Rosen from "Entertainment Weekly" deemed the track "exhilarating". According to Aguilera; lyrically, "Ain't No Other Man" is not a love song, but actually intertwines with the events that she experienced in real life. The song seems to be about Aguilera's husband, Jordan Bratman, but is really simply about feeling good. During an interview with MTV News, Aguilera said of the song, "I wanted to make it light and easy for people to dance to and sing along to... Lyrically, I just got married, so it's about someone in particular, but it's all about feeling good and not taking anything too seriously".