The Swans left it late to record their first league victory in eight matches, Bony ramming home a loose ball following a Ki Sung-yueng corner to lift his side above Crystal Palace in the standings.
The striker's second goal in as many games leaves visiting manager Alan Pardew still winless since taking charge of the Baggies, who only remain outside the relegation places on goal difference.
Pardew's last trip to the Liberty Stadium was back in November 2016, when his Crystal Palace side lost 5-4 to their hosts, yet any hope of a pre-Christmas feast of goals looked unlikely between two clubs with a combined total of 20 in the league prior to kick-off.
It appeared the battle between the two strugglers would end in stalemate until Bony popped up with an emphatic finish, securing three crucial points that will ease any pressure on his manager, Paul Clement.
YEEEEEEEEEEESSSSSSS!!!!!!!!! pic.twitter.com/FWcJv1gSp5— Swansea City AFC (@SwansOfficial) December 9, 2017
Critical of his side after surrendering a lead to lose 2-1 at Stoke City a week ago, Clement responded by making four changes, including handing Wayne Routledge a first start since the opening day of the season.
Top scorer Tammy Abraham dropped down to the bench while Renato Sanches failed to even make the matchday squad, a new low for the on-loan midfielder in what is turning out to be a disastrous spell in south Wales.
Deckchairs suitably shuffled on a Swansea ship in danger of sinking out of the top flight, Clement saw his side pose the greater threat in their pursuit of a first win since October 14.
Jake Livermore nearly helped out the hosts by scoring in his own net, the midfielder inadvertently flicking on a free-kick that clipped the far post and stayed out.
Alfie Mawson then carelessly nodded over when picked out perfectly by Routledge's teasing cross soon after, wasting easily the best opportunity in a first half that failed to warm up until the closing minutes
West Brom did manage the only shot on target before the break, yet Pardew's attacking line-up caused more work for referee Mike Dean - who booked Claudio Yacob and Sam Field - than home goalkeeper Lukasz Fabianski.
Bony saw a low shot slip narrowly wide before Ben Foster was finally forced into a save when needing to turn aside a drive from substitute Jordan Ayew that looked to be squeezing inside the goalkeeper's left post.
However, Swansea's incessant pressure was finally rewarded from a set-piece opportunity, as Bony scored in back-to-back Premier League games for the first time since December 2014.
2 - Wilfried Bony has scored in consecutive Premier League games for the first time since December 2014 (also for Swansea City). Wild. pic.twitter.com/yZrxwBvh4Z— OptaJoe (@OptaJoe) December 9, 2017
Abraham wasted a glorious chance to double the lead in stoppage time, lifting the ball over Foster but also wide of the target when clean through, but Swansea held on for a much-needed result ahead of the midweek visit of leaders Manchester City.
Key Opta stats:
- The Swans ended a run of seven Premier League games without a win (D1 L6).
- The Baggies are now winless in their last 14 Premier League matches (D7 L7), their longest run in the top flight since a 16 game streak between February 2006 and August 2008.
- Wilfried Bony has scored two goals in his last two Premier League games – as many as he had in his previous 28 in the competition.
- Indeed, it's the first time the Ivorian has scored in consecutive Premier League appearances since December 2014.
- Swansea had three shots on target in this match – only twice have they managed more in a Premier League game this season (4 vs Newcastle and Leicester).
- After having the first shot on target in the 22nd minute of this match, the Baggies didn't register another one in the entire match.