[1] "Who's in Your Head" has been described as "another breezy tune" that is "an upbeat pop number bolted onto a funky guitar refrain and featuring some chandelier-busting falsetto", as well as "bring[ing] the funk".

[4] On September 5, 2021, the Jonas Brothers performed the song on their Remember This Tour at the Red Rocks Park and Amphitheatre in Colorado.

They posted a video of it to the band's TikTok account, writing "Right now you're listening to our new song...we just performed it for the first time at Red Rocks on the Remember This tour.

[7] Jason Lipshutz of Billboard praised co-writers Max Martin and Rami Yacoub, proclaiming them as "a 15-year reunion of pop powerhouses responsible for penning songs like Britney Spears' "Oops!

I Did It Again" and NSYNC's It's Gonna Be Me" and went on to state that "even those unaware of the behind-the-scenes players, however, will lap up the latest JoBros offering, an ode to envy straight out of the Nick Jonas "Jealous" playbook with a delectable guitar riff that would have fit on their Happiness Begins album".