Tennant will play a Detective Inspector, while Darvill takes on the role of a Priest in the eight-part series which is titled Broadchurch and looks at the lives of people living in a small town after the body of a young boy is found on a beach.
Chibnall says: "Broadchurch focuses on a small British community which finds itself at the eye of a storm. In the wake of one boy's death, the residents of Broadchurch come under scrutiny and suspicion.
"It's a story of scale and intimacy, as the lives of the characters are laid bare."
Production will begin later this year on location in Portishead near Bristol and Dorset.
(Source: Press Association)