Marianne Jean-Baptiste, James D'Arcy, Eve Myles and Phoebe Waller-Bridge have joined the cast of the crime drama.
Torchwood and Frankie star Eve Myles will play a central role in the new series, along with Bad Education's Waller-Bridge. Details of the characters are currently being kept under wraps.
Creator and writer Chris Chibnall said: "As if we didn't have enough fabulous actresses, it's a thrill to be joined by Wales's finest, Eve Myles. Having worked together on Torchwood, it's a joy to be able to welcome her to Broadchurch.
"And anyone who's seen Phoebe Waller-Bridge perform knows she's already on the way to being a superstar. We're lucky to have them both on board".
Oscar and BAFTA-nominated Marianne Jean-Baptiste (Secrets & Lies, Without a Trace) will play a leading role in the series.
"We're over the moon to have wooed Marianne