The duo, who played DI Alec Hardy and DS Ellie Miller in the original run, will be re-joined by Arthur Davill (back as Reverend Paul Coates), Jodie Whittaker and Andrew Buchan (murdered schoolboy Danny Latimer's parents).
The storyline remains a secret but, if it’s anything like the first, millions of us will be hooked yet again. Last spring saw over 8 million viewers tune in to see Miller's husband Joe revealed as the murderer in a nail-biting finale.
"The reaction to Broadchurch from UK viewers has been incredible," executive producer Jane Featherstone told RadioTimes.co.uk. "So, we'd like viewers to enjoy the new series knowing as little as possible about what’s to come and for the story to unfold in real time."
Steve November, ITV's director of drama, added that the production team really are remaining "tight-lipped". "Suffice to say Chris (Chibnall) has delivered as always and the scripts are just as exciting as the first series," he said.
It remains to be seen whether Charlotte Beaumont, Will Mellor, Vicky McClure and the acclaimed Pauline Quirke will reprise their roles.
Filming is set to begin in Dorset shortly, with James Strong directing the first two episodes. Strong helmed five episodes of the first series.
Tennant's character was last seen suffering a heart attack, leading many fans to doubt his reappearance. The Doctor Who star has also been shooting Broadchurch's US remake, Gracepoint, with Breaking Bad's Anna Gunn, leading to concerns over his busy schedule.
Viewers have known that a second series is coming since the end credits of the last show broadcast the words "Broadchurch will return" to great excitement.