Downton Abbey star Joanne Froggatt, World Without End's Ben Chaplin and Silent Witness actress Emilia Fox have signed up to appear in an episode written by Elinor Cook.
Each 30-minute episode of the Dominic Savage-directed drama will centre around a provocative incident told from separate viewpoints.
Cook's episode focuses on a man who is married to two women as he leads a secret double life.
Nick Payne will write two episodes of the series, starring previously announced cast members Olivia Colman, Alison Steadman and Steve Oram, while Sarah Solemani will write and star in her own instalment as a bride-to-be who discovers her fiancé was once accused of a shocking crime.
Ben Ockrent will pen an episode starring Cuckoo's Helen Baxendale, Anthony Welsh and Waterloo Road star Paige Meade, which revolves around a girl who turns up out of the blue claiming to be a boy's unknown sister.
Head of Television for Working Title Television Juliette Howell said: "I'm thrilled that Dominic has assembled such a stellar line up.
"It's hugely exciting to see so many of our finest actors bringing these original and distinctive new voices to life on BBC One."
Producer Guy Heeley added: "It's really exciting to see these bold and ambitious stories being brought to life in such a compelling way by this incredibly high-calibre cast."
The Secrets started shooting last month and will be broadcast later this year.