The duo have signed one-year contract extensions with the Baggies.
The pair were due to see their existing deals xpire at the end of this season.
McAuley told the club’s official websit: “It’s great for both Jonas and I. When you’re settled somewhere and you enjoy it, and you enjoy the football and the people you work with, it’s an easy decision to make.
“The time Jonas has been here has been fantastic and I’ve really enjoyed the time I’ve had with him and with the Club.
“Speaking to the Club and the plans they have moving forward, hopefully we can step on.
“Since I’ve been here it’s always been about progression, we staggered a little bit for a couple of years, but I think this season we’ve progressed again and hopefully with a few additions we can establish ourselves as a top-10 Club.”
Olsson said: “It’s good to be part of the squad for another year, it makes it nine for me and six for Gareth.
“It’s nice to be part of this Club and I’m happy to play with Gareth for another year.
“When you make decisions about your future, there’s certain things you weigh up and, for me, it really has been about being part of this group for another year.
“Both of us have been here a long time but I think we can agree that the dressing room we have now really is something special.
“I’m really happy and proud to be part of this team and this league for another season.”
