The Baggies failed to carve out any clear-cut chances and they saw captain Jake Livermore sent off for a high-footed challenge on Fraizer Campbell later on in the clash.
Huddersfield saw out the game and have found themselves within a point of a play-off position.
Tactical stubbornness from Ismael
Albion manager Valerien Ismael has come under fire from West Brom supporters after remaining rigid in his tactical approach throughout the game.
Ismael hasn't differed from his 3-4-3 formation since joining the club in the summer, and pressure is beginning to mount with calls for the Frenchman to change his ways.
The Baggies have been persistently vulnerable to straight balls over the top of their defence, this is a result of the high defensive line that the former Barnsley boss persists in playing.
The Terriers’ first goal came from this situation, as Lewis O'Brien's straight ball left the defence trailing and allowed Sinani an easy chance on goal.
Despite facing a fellow midfield two in O'Brien and youngster Scott High, both Mowatt and Livermore looked out of position constantly throughout the game, allowing the Terriers midfield pairing plenty of space to manoeuvre.
If Ismael's rigidness and unwillingness to change continues, along with the declining results, then this long-term project may just be cut short.
Play-off push for the Terriers
Carlos Corberan's overachievement with this Huddersfield side has brought a lot of praise from pundits as they remain within a fingertip of the play-offs.
The Terriers showed defensive solidity and resilience to limit Albion to very few clear-cut chances.
Corberan completely stumped Ismael and picked himself against the Frenchman well to completely stifle any threat that the Baggies posed.
If the Town continue to surprise and make the top-six, they've proved that by beating West Brom they can take the better teams in the league all the way.
The Terriers face fellow play-off contenders QPR on Wednesday night away at the Kiyan Prince Foundation Stadium and will aim to continue winning ways and roll into the top-six.
Albion will look to stop the rot in their away form by preventing a fifth consecutive defeat on their travels, as they face Blackpool away at Bloomfield Road, a stadium they haven't won at since 2010.