Winger Matt Phillips made the decisive contribution just before the half-hour mark, racing clear of the Magpies’ backline and thumping the ball past Martin Dúbravka.
Newcastle’s best spell of the game came late in the first half, with Mo Diamé and Dwight Gayle both threatening an equaliser. On the whole, though, the home side lacked the energy and creative spark that had been evident in each of their last four outings at St. James’ – all of which had yielded three points.
West Brom looked capable of adding to their lead during a largely forgettable second period, though the West Midlands outfit will still drop out of the top flight should Swansea City overcome Chelsea in the day’s evening fixture.
The Baggies fired a warning shot 12 minutes in, going close through James McClean with the first chance of the game. DeAndre Yedlin lost his balance as he looked to show McClean down the wing, allowing the Irishman the chance to step back inside before drilling narrowly off-target.
Though Gayle got an effort away for Newcastle after pouncing on a loose ball, it was West Brom who were looking the more likely to draw first blood. Phillips did well to chase what appeared a lost cause deep on the right, delivering a cross from the byline which Jay Rodriguez failed to make the most of.
Two minutes later, though, Phillips was the recipient of a fine ball – this time from Jake Livermore – and the Scot bore down on goal before lashing beyond a helpless Dúbravka.
It was the wake-up call the Magpies needed. They finally got going in the attacking third during the final 15 minutes of the half. Kenedy was the first to go close, playing a one-two with Ayoze Pérez before clipping the base of the far post with a swerving shot.
Just before the break, Diamé saw a left-footed strike take a nick off the Baggies’ Ahmed Hegazi, and from the resultant corner, only a superb Ben Foster save kept Gayle’s header from hitting the net.
After weathering something of a storm, Albion ought to have doubled their lead early into the second half. United failed to deal with a McClean cross from the left, and again, a stray ball looked to be dropping kindly for Rodriguez. Once more, though, the forward failed to connect properly, and the opportunity went begging.
With Newcastle enjoying more of the ball but struggling to find a cutting edge in front of goal, the Baggies continued to look a threat on the counter. Chris Brunt fired wide with a speculative attempt, before Rodriguez and McClean failed to make anything come of another promising situation.
Rafa Benítez introduced both Islam Slimani and Joselu as United looked for a way back into the game. The latter met a Yedlin cross five minutes from time, but his downward header bounced wide of the near post.
That was just about it for Newcastle, who lost a Premier League game on home soil for the first time since Boxing Day.