Despite being without captain Vincent Kompany, Sergio Aguero and Edin Dzeko through injury, Manuel Pellegrini's side took advantage of a dismal opening period from the hosts to keep pace with leaders Chelsea.
The visitors were handed an early gift courtesy of Ben Foster, as the West Brom goalkeeper dropped a looping Jesus Navas cross eight minutes in.
Midfielder Fernando took full advantage to cleverly register his first goal for the club, with ex-City defender Joleon Lescott also aiding his former employers' cause soon afterwards.
David Silva went down under Lescott's challenge inside the area and, when Yaya Toure subsequently doubled City's advantage from the penalty spot, they were well on course for a ninth consecutive win in all competitions.
Despite rarely getting out of first gear, the champions were three to the good 11 minutes before the interval when Silva calmly steered a strike past Foster.
An improved defensive effort from West Brom kept the score respectable after the break, and they finally got on the scoresheet themselves when Brown Ideye turned the ball home after a scramble late on, but it proved too little, too late for Alan Irvine's men.
City had the first sight on goal when stand-in striker James Milner prodded Silva's flick goalwards, only to be denied by Foster's legs - before the home goalkeeper undid his good work by fumbling a deflected Navas delivery in the six-yard box.
Fernando was the man on hand to acrobatically hook the ball home and open his account for the club, with things going from bad to worse for Irvine's men five minutes later as Lescott stretched to make a challenge and brought down Silva inside the area.
Toure confidently dispatched the penalty to Foster's right to put the visitors in cruise control.
The returning Saido Berahino almost reduced the arrears when he fired wide following a quick break, while Youssouf Mulumbu - also recalled to the West Brom line-up - tested Joe Hart with a fierce effort just before the half-hour mark.
But despite offering a threat going forward, West Brom remained susceptible at the back and that proved to be their downfall before the break, Silva the man to benefit this time.
Following a quick counter, the Spaniard expertly curled Navas' cut-back home left footed to leave West Brom facing an uphill battle.
In stark contrast to the first half, the hosts had the better of the play early in the second period, despite worsening wintry weather conditions in the West Midlands.
Hart was required to deal with a dangerous Craig Gardner cross before Navas fired City's first effort of the half off target.
With three minutes left West Brom did pull one back when substitute Ideye helped the ball over the line following a corner kick to register his first Premier League goal, but a famous comeback was never on the cards.
Although Irvine may take heart from his side's improved resilience after the interval, a fourth defeat from their last five top-flight home outings will be a cause for concern for West Brom, while City's bid to reel in Chelsea in the title race remains very much on course.
