"Hollaback Girl" received mixed reviews from music critics. Yahoo! Music's Jennifer Nine described it as a "stomping, stripped-back" track, and Stephen Thomas Erlewine of AllMusic noted that it had the "thumping, minimal beats" of The Neptunes. Richard Smirke of Playlouder called it "a trademark Neptunes hip-hop stomp." In his review of Love. Angel. Music. Baby., Rob Sheffield of Rolling Stone gave the song a positive review, writing that "Stefani's gum-snapping sass brings out the beast in her beatmasters, especially the Neptunes in 'Hollaback Girl'." Blender listed it as the 11th best song of 2005, and the song tied with Damian Marley's "Welcome to Jamrock" for number five on the 2005 Pazz & Jop, a survey of several hundred music critics conducted by Robert Christgau.
On the other hand, Jason Damas, in a review for PopMatters, felt that the song sounds "almost exactly like Dizzee Rascal", and added, "Lyrically, this is where Gwen sinks the lowest here, especially on a breakdown where she repeats, 'This shit is bananas / B-A-N-A-N-A-S!' several times". Eric Greenwood of Drawer B called the song "moronic and embarrassingly tuneless," while also writing "I'd quote the lyrics, but they're so bad, I almost feel sorry for her. A 35-year-old woman singing about pom-poms and 'talking shit' in high school betrays such a delusional self-image that it's hard not to be taken aback. And on top of that, The Neptunes' beats are clunky and the production is senselessly bombastic." Nick Sylvester of Pitchfork also criticized the track, referring to it as a "Queen pastiche which has about as much club potential as a 13-year old with a milk moustache and his dad's ID". However, despite this initial review, Pitchfork would later place the track at number 35 on its list of the Top 50 Singles of 2005, and at number 180 on its list of The Top 500 Tracks of the 2000s. Maxim was unimpressed with the song, and in its October 2005 issue, published a list of the "20 Most Annoying Songs Ever" with "Hollaback Girl" in first place. Cat Conway of Drowned in Sound gave the song a negative review, saying "Hollaback Girl" sees Gwen Stefani getting a big lick off the Neptunes flavour at the Hot Producer Baskin-Robbins, delivering vocals that sound like she needs a Sudafed."