"You Ain't Seen Nothin' Yet" is the ninth track on the album. It is a pop-rock track that lasts for three minutes and 14 seconds. It was written in the key of B Major.  Musically, it has been compared to some of Lavigne's older tracks such as "Sk8er Boi" and "Girlfriend".
"You Ain't Seen Nothin' Yet" received mainly mixed reviews from critics, who found the song to be catchy and comparable to some of her older material, but overly generic. Nick Catucci of Entertainment Weekly gave a mixed review of the song, calling both "You Ain't Seen Nothin' Yet" and "Give You What You Like the album's "sexual confusion songs" and going on to compare "You Ain't Seen Nothin' Yet" to the work of Taylor Swift. Craig Manning of Absolute Punk
also gave the track, along with "Sippin' On Sunshine", a mixed review, calling them "enjoyable but generic Katy Perry pop".
Jason Lipshutz of Billboard gave a positive review of the track, comparing it to tracks from The Best Damn Thing, and going on to say that it wasn't as "solid" as some of the other uptempo tracks on the album. He concluded his review of the track by praising the song's bridge.