The principal cast included KJ Apa, Lili Reinhart, Camila Mendes, Cole Sprouse, Marisol Nichols, Madelaine Petsch, Mädchen Amick, Mark Consuelos, Casey Cott, Skeet Ulrich, Charles Melton and Vanessa Morgan returning from the previous season.

Archie learns that his uncle Frank has a troubled past, and Jughead gets in deeper with the Quill & Skull Society after discovering that he has earned an interview with Yale.

On game day, Frank gives Munroe drugs so that he can play and Cheryl locks Appleyard in a classroom so she can have the squad to herself.

They meet with Mr. Chipping's wife, who says Donna was lying about the affair she had with him, and Moose, who says that Bret videotaped him having sex.

Veronica catches up with her friend Katy Keene in New York, and after she returns learns that her father is ill. Nick St. Clair appears, and Toni, Kevin, and Fangs turn the tables on him, forcing him to leave Riverdale from Cheryl.

Jughead gives Bret the win in their duel, and Betty reveals that she was able to sneak a tape labeled "Donna" from Stonewall Prep.

[29] On July 22, 2019, it was announced Shannen Doherty would appear during the tribute episode to Luke Perry as a guest star.

On July 30, 2019, it was announced that Sam Witwer had joined the cast playing the recurring character of Mr. Chipping, Jughead's teacher.

[32] On September 5, 2019, Mishel Prada joined the cast as Hermosa Lodge, a private investigator and half-sister to Veronica.

[33] On October 21, 2019, it was announced Ryan Robbins and Timothy Webber would join the recurring cast playing Frank Andrews, Fred's young brother and Archie's uncle, and Forsythe Pendleton Jones I, F.P.

[37] On March 11, 2020, production of the season was shut down indefinitely after a member of the cast or crew came in contact with an individual who tested positive for COVID-19.

The Complete Fourth Season was officially released on DVD in region 1 on September 22, 2020, by Warner Archives.