The Baggies will be boosted by two of their stalwarts agreeing one-year contract extensions.
Olsson has been at the Hawthorns since 2008, chalking up 247 appearances.
The Swede has played 23 Premier league games for the Baggies this year and has helped them on their way to the eighth best defensive record in the league.
McAuley joined from Ipswich in 2011, and has since made 171 appearances for the Midlands outfit.
The Northern Ireland international has made 28 Premier league appearances for West Brom this term, and has formed a consistent partnership with Olson.
Both player's deals were set to expire in the summer, so the confirmed extensions will be a major boost for Baggies manager Tony Pulis and the West Brom faithful.
McAuley told wba.co.uk of his satisfaction in resolving his future before Euro 2016:
"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."
He also spoke highly of his team-mate Olsson, praising his longevity:
"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."
The Baggies currently sit comfortably in 14th position in the league, a full 13 points clear of 18th placed Sunderland, and play host to Watford tomorrow in the Premier league.