Wayne Routledge's double and Michu's strike in the first half proved to be enough for the Swans to bag maximum points at the Liberty Stadium.
Romelu Lukaku's goal in first-half injury-time was the only highlight for Steve Clarke's side in a largely uninspiring display that saw them drop to fourth in the table.
The first chance of the game fell to the Swans as early as the second minute. Pablo Hernandez released Michu from the left with a ball over the top of the West Brom defence, but the Spaniard saw his left-footed shot from a narrow angle come off the post.
Michu, though, did not have to wait long to score as he slotted home Pablo's low cross from the left in the ninth minute.
Two minutes later Pablo again turned provider, this time feeding Routledge from the left with a well-measured cross that the midfielder turned in off Jonas Olsson.
Swansea continued to dominate proceedings at the Liberty Stadium, with West Brom creating their first chance only on the half-hour mark when Peter Odemwingie fired just wide from outside the box.
It became 3-0 to the Welsh club in the 39th minute when Nathan Dyer and Hernandez helped tee up Ben Davies for his left-wing cross across the face of the goal that Routledge fired home with ease.
Swansea could have gone into the break 4-0 up had Michu been able to connect with Hernandez's cross from the left after finding himself in a very good position.
Instead Michael Laudrup's side conceded on the stroke of half-time when Lukaku fired home from close range after receiving a flick-on from Swansea's Ki Sung-Yueng following a corner.
The Baggies started the second half on a brighter note with Lukaku first shooting just wide and then floating in a cross that was cleared just in time by Ashley Williams, before Odemwingie tried his luck but in vain.
Michu came close to adding to his tally on two occasions in the final 20 minutes and Ki hit the side-netting with a curling free kick, as the Swans secured a comfortable win.