The Northern Ireland international has played every minute in the Premier League this season and is currently the division's oldest outfield player
McAuley turns 38 in December and his old contract was due to expire in the summer but he has now committed his future to the Baggies until 2018
"It's very pleasing," he told the club's official site
"I'd like to thank the club, the gaffer and everyone here who helps me to stay fit to be able to play at this level.
"It's very, very pleasing
When I signed I just wanted to play in the Premier League and I knew that wasn't a given when I came here
But I've still got that desire sitting here today.
"I don't think that will leave me
It's a good thing because it keeps you motivated, keeps you pushing forward."
McAuley has scored seven goals for the Baggies this season and has made 208 appearances for the club since joining on a free transfer in 2011
And the former Leicester and Ipswich centre-back said he would not have signed a new deal unless he was confident he could cope with the Premier League
"I've based my decision on physically being able to do it," he said, ahead of Albion's trip to Manchester United on Saturday
"If I didn't think I could I wouldn't hang about
The tests don't show any signs that I can't cope with it.
"I've worked for a living outside the football bubble and I will more than likely have to go back there one day.
"But as long as you can do this, the best job in the world, then you should continue and I'm not going to turn my back on it."
Source : PA
Source: PA