Dorrans signs new Baggies deal
A 12-month option on Dorrans' previous deal had already been activated by Albion this summer and he has now put pen to paper on fresh terms that commit him to the Baggies until 2017.
The 27-year-old Scotland international has been at West Brom since the summer of 2008.
And he told the club's official website: "I'm happy to get my new contract finalised.
"We've been in talks for a couple of months and I'm glad to get it over the line. I'd like to thank my agent and the club for getting it sorted out.
"I've enjoyed my six years at Albion, I'm looking for a testimonial now!
"It's been a good six years and that's the reason why I've signed the extension. I'm looking forward to getting going now for the new season."
Since joining from Livingston, Dorrans has made a total of 167 appearances for Albion in all competitions and scored 25 goals.
After only featuring once in the Premier League between September and March last term, he finished the campaign by starting every one of the Baggies' last 10 games under now-departed head coach Pepe Mel.
Dorrans said: "It was a difficult start for me last season but it was about getting in the team and staying in there, and that's what I'm hoping to do this year.
"I'm aiming to get in at the start of this season and stay in the team for the rest of the campaign."