The channel has ordered six new episodes of the drama, about a group of thirty-something women looking for romance.
Stars Sarah Parish, Sharon Small, Orla Brady and Shelley Conn will all return to filming in September.
Julie Gardner, the BBC's head of drama in Wales, said: "The first series really struck a chord with the BBC audience and we're thrilled to be welcoming the characters back so we can further enjoy the thrills and spills of their messy, romantic lives."
Douglas Rae, executive producer of the show at Ecosse Films, said it had received a "phenomenal" response to Mistresses.
"In the new series we will learn a great deal more about Katie, Trudi, Siobhan and Jessica as well as the men, and women, in their lives," he said. "We are planning plenty more surprises and maybe even a couple of new faces will be joining the cast – watch this space!"
This year's run attracted an average audience of 5.2m on BBC One at 9pm on Tuesdays.