Doris (KYLA PRATT) is a north Philly high school student who's having a bad year. Not only does she have few friends, but her nice foster sister, Lauri (DANIA RAMIREZ), is very popular and has even taken over her spot as the star of their school's track team. After not being invited to a party, Doris is at home watching the "Fat Albert" cartoon when one of her tears hits the remote.
As the cartoon plays on the TV, the characters inside it take note of Doris' sadness and Fat Albert (KENAN THOMPSON) decides that she needs his help. Accordingly, he comes out through the TV and arrives in her living room in human form, followed by his friends Rudy (SHEDRACK ANDERSON III), Mushmouth (JERMAINE WILLIAMS), Bill (KEITH D. ROBINSON), Bucky (ALPHONSO McAULEY), Old Weird Harold (AARON A. FRAZIER) and Dumb Donald (MARQUES B. HOUSTON).
Doris initially thinks she's lost her mind and while she eventually accepts that they're real, she refuses to admit that she has a problem. Fat Albert insists that she does and is adamant about helping her, but she states that they have to go back to their show the following afternoon when it airs again.
Fat Albert sets out to get Doris some friends, but finds himself attracted to Lauri at the same time. That doesn't sit well with Reggie (OMARI GRANDBERRY), another student who, with the help of friend Arthur (J. MACK SLAUGHTER, JR.), sets out to make Fat Albert and his friends look bad.
With time running out and their vivid pastel colors starting to fade the longer they stay in the real world, Fat Albert and his friends race to accomplish their mission.