Also returning from the earlier movies are Jim Broadbent, Gemma Jones, Shirley Henderson, James Callis and Sally Phillips.
Colin Firth, however, will not be back to play fan-favorite Mark Darcy.
Joining the ensemble for what is being billed as "one last chapter" will be Emma Thompson, Isla Fisher, Chiwetel Ejiofor and Leo Woodall.
Directed by Michael Morris and based on Helen Fielding's novel, the latest film will also be released internationally in theaters, starting Feb. 12.
"Bridget is alone once again, widowed four years ago, when Mark was killed on a humanitarian mission in the Sudan," a synopsis said.
"She's now a single mother to 9-year-old Billy and 4-year-old Mabel, and is stuck in a state of emotional limbo, raising her children with help from her loyal friends and even her former lover, Daniel Cleaver," the summary added.
"Pressured by her Urban Family -- Shazzer, Jude and Tom, her work colleague Miranda, her mother, and her gynecologist Dr. Rawlings -- to forge a new path toward life and love, Bridget goes back to work and even tries out the dating apps, where she's soon pursued by a dreamy and enthusiastic younger man."