Broadchurch producer Richard Stokes hinted to fans of the show that there would be a major twist at the end of the episode - and his comments referred to the written text "Broadchurch will return", which appeared on screen after the end credits.
The murder case in the eight-part drama, which centred on the murder of schoolboy Danny Latimer, was all resolved by the end of the episode. The detectives in the case DS Miller (Olivia Colman) and DI Hardy (David Tennant) appeared to have retired from policework, so it's not clear which actors will be involved in the second run.
Broadchurch has been an overwhelming ratings hit for ITV, winning critical acclaim and generating huge publicity around the whodunnit mystery.
The show's writer Chris Chibnall said on Twitter this evening: "I'll shut up in a second, but final thanks to the amazing cast, crew, production company & network who all kept our secrets.
"Now it's time for a big drink. Just, thank you."
Jodie Whittaker, Andrew Buchan, Vicky McClure, Arthur Darvill, David Bradley, Pauline Quirke, Jonathan Bailey, Carolyn Pickles and Will Mellor all starred in the first series.
ITV's Peter Fincham commented on the recommission: "We're delighted to be commissioning a second series of Broadchurch.
"From the moment the murder scene was discovered, viewers became gripped by the series, and we've been genuinely thrilled by the audience response. David and Olivia's performances and Chris's cleverly crafted scripts have created a truly compelling drama."
Chibnall said: "The whole Broadchurch team has been delighted and properly gobsmacked by the response from ITV viewers.
"When I first talked to Peter Fincham and Laura Mackie, ITV's Director of Drama, about Broadchurch, I mentioned that if people liked it, there was another very different story we could tell afterwards. I'm really thrilled we're going to tell that story too."
ITV said that details on the casting and story for series two would be "kept tightly under wraps". Production will start in 2014.