Trai Hume scored the only goal of the game in a clash of two promotion hopefuls, extending West Brom's winless run.
The Sunderland left-back struck a phenomenal free-kick, stunning West Brom keeper Joe Wildsmith at his far post.
Despite a performance far from their best, the visitors overcame West Brom to further consolidate their play-off position.
The result dampens The Baggies’ promotion hopes, falling to eighth after results elsewhere didn't go their way.
Story of the match
West Brom started the clash as the better of the two teams, pushing for a result that would see them end the day in the play-off positions.
Tony Mowbray's men came closest in the first 10 minutes, with Mikey Johnston's cross to Grady Diangana cut out before Diangana’s cross landed at Armstrong's feet, who wasn’t expecting it.
The visitors showed their capabilities with Romaine Mundle's cross blocked before his volley sailed over the bar. Despite chances not coming often in the game for Sunderland, their threat was evident.
West Brom came closest to breaking the deadlock, with Darnell Furlong's volley dramatically cleared of the line.
Despite the lack of chances, it was Sunderland that scored the first goal. Following a foul from Diangana, Trai Hume's free-kick found the top right of the corner. Seemingly, Wildsmith wasn't expecting the shot and floundered on his line.
West Brom's Mikey Johnston came close to equalising, he cut inside but his shot went narrowly wide. His signature move was repeated throughout the game, but unfortuntely for the Irishman it didn't come off.
Nigh on the end of the half, Diangana's 40-yard shot rocketed narrowly wide of Patterson's goal, with Callum Styles almost finding Diangana with a cross that was narrowly cut out.
Following a break at halftime, which consisted of a fantastic tribute to West Brom's See Us to Believe Us campaign, it was the Albion that created the bulk of the chances.
Following sloppy play from Sunderland, Diangana won the ball back, his through ball then found Karlan Grant, but it was intercepted and volleyed clear for a corner.
Throughout the course of the second half, West Brom were really piling on the pressure with attack after attack battering the Sunderland back line. Yet another Mikey Johnston signature cut in and shoot was blocked with the rebound from Adam Armstrong fired over the bar.
Sunderland were able to formulate attacks as the half went on, with Jobe Bellingham finding himself in a shooting position but it was easily saved by Wildsmith.
West Brom came the closest in the second half, with Furlong's cross finding man mountain Kyle Bartley whose header forced Patterson into an excellent save.
Patterson was called into action once more before the end of the game with Molumby's searching free kick finding Bartley again. but this time his header was easily caught.
Play-off's looking likely for Sunderland
Le Bris' Sunderland sit in fourth place and after this win against the Albion, 16 points clear of seventh and eight away from second.
They have a respectable three wins, two draws and one loss in their last five games, which is much more consistent form compared to that of the other play-off contenders below them.
They've shown their ability to conjure goals from all over the pitch, with a defender scoring the game maker today.
They play fellow play-off contenders Norwich City on Tuesday and will hope to carry on this form.
Top six now out of West Brom's hands
West Brom are in a rut of form under Tony Mowbray, with their last five games resulting in two losses, two draws and a win. Far from play-off contending form.
Their poor run of form threatens to carry on with difficult fixtures like Bristol City, Watford and Coventry City in their next three games. All of which are vying for a top six spot.
Star Player - Mikey Johnston
The Irish winger was the dominant force in West Brom's attack today and was one of the positives for them on an otherwise disappointing afternoon.
His constant threat going forward with crosses and shots created chance after chance for West Brom and through him was the reason they came close to scoring.
