Season 4 of The Most Popular Girls in School premiered January 6, 2015. It centers around Brittnay Matthews getting revenge on both Mackenzie Zales for what she did to Brittnay in season 3 and for burning her car to rubble, as well as everyone else that has wronged her in the past. A teaser was released on October 7, 2014. It has twelve episodes including a three-part finale, making it the shortest season so far.
Season 4 opens with Mackenzie and the rest of the squad (except Brittnay) joyfully walking the halls of their school enjoying the fact that there's seemingly no more drama between them and anyone else, as they've won all the championships, and are glad they can enjoy the final few weeks of junior year in peace. But, this hope is shattered when they discover their lockers have been defaced. Mackenzie, in a rage, orders Shay to gather "everyone" together in a classroom to find out who destroyed their property. No one they call actually did it; Rachel, before the assembly leaves after stating they don't care for the drama that surrounds the cheer squad constantly, gives Mackenzie a speech about Mackenzie unleashing something bad upon the school after she unleashed "an evil we all fought so hard to control". This reminds Mackenzie about something that happened in the past, and she realizes Brittnay is the one who destroyed their lockers.
In the bathroom, where Brittnay is at work spray-painting crude things on the wall and bashing the stall doors off their hinges, Trisha finds her and Brittnay lets her know she considers Trisha a true friend, and promises her that she'll get her revenge on Mackenzie, effectively stating she is threw with her as a friend. When Brittnay exits Mackenzie finds Trisha, and tells her that Brittnay's rage comes from an incident that happened in the third grade.
As with each new season of the series, the creators of MPGIS have set up an Indiegogo campaign to help fund season 4. The creators plan for season 4 to have "some crazy cinematic elements" the likes of which the series has never had before. The new season will be produced at the YouTube Space in Los Angeles, California; unlike the previous seasons where Mark Cope both directed and animated each episode singularly, the creators plan on bringing in a whole crew in hopes it will make the show "like a professional animated television show". The money funded will be used for the props, actors, animation crew, fabrication, and equipment. As of November 5, 2014, the campaign reached $18,000 in pledges, well over its original goal.