The film stars Rebel Wilson (who also produced) as a 37-year-old woman who awakens from a 20-year coma and decides to go back to high school to earn her diploma.

[3] In 1999, after a disastrous birthday party at the local "cool" spot, Rock N' Bowl, with her friends Seth and Martha, 14-year-old Australian immigrant Stephanie Conway decides to become one of "the populars".

In 2002, Stephanie plans to win prom queen in hopes of becoming like Deanna Russo, an alumna of her high school who got married after graduation, and now lives in a mansion.

Stephanie works to regain her former popularity through social media, finally succeeding after a risqué cheer routine she choreographs without Martha's permission goes viral at a pep rally.

Afterwards, they have drinks at the Rock N' Bowl and Stephanie confesses that she wants to be elected prom queen so badly to make her late mother proud.

She makes up with Martha, finally kisses Seth, and welcomes Tiffany to join them on stage as she gets to pull off the move she had not got to do twenty years earlier.

[7] In July 2021, Jade Bender, Michael Cimino, Jeremy Ray Taylor, Avantika, Joshua Colley, newcomer Ana Yi Puig, Molly Brown, Zaire Adams, and Tyler Barnhardt were added to the cast.

The website's consensus reads: "In spite of a premise that promises to highlight Rebel Wilson with the appropriate level of pomp and circumstance, Senior Year is strictly remedial.

"[13] In a two-star review, Christy Lemire of RogerEbert.com commended the performance of Angourie Rice, citing that "she accurately channels Wilson's sly, deadpan delivery".

[14] The Guardian criticized the film's humor, calling it "an R-rated comedy that wants to be both sweet and salty, a balance it never manages to perfect".