Manuel Pellegrini's team made it seven wins from as many Premier League matches at the Etihad Stadium against Swansea on Sunday but they arrived at the Hawthorns with one win and four defeats in six attempts outside Manchester.
Sergio Aguero's 17th goal in as many starts this term and Yaya Toure's eighth of the season made light of those struggles and City should have had more than those two wonderfully crafted team efforts to show for a dominant opening 45 minutes.
Toure sealed the victory with a 73rd-minute penalty before West Brom rallied late on through Costel Pantilimon's own goal and Victor Anichebe's injury-time strike, but City retained their position in third on a night when the Premier League's top five were all victorious.
Influential captain Vincent Kompany returned from two months on the sidelines with a thigh injury to start for the visitors as both teams made three changes to their weekend line-ups.
Edin Dzeko, scorer of all three City goals in two wins over West Brom last season, was recalled and found himself instantly involved - chesting down Toure's pass for Aguero to fire wastefully wide.
Aguero soon atoned for his error, emphatically converting Pablo Zabaleta's cutback to cap a superb ninth-minute team move.
West Brom sought an instant response and low drives from Morgan Amalfitano and Saido Berahino - fresh from signing a new contract during the week - flew wide, but Aguero linked seamlessly with Dzeko once more to crash a shot of his own into the advertising boards.
City doubled their advantage in the 24th minute with another scintillating passing move.
Aguero and Samir Nasri combined for Aleksandar Kolarov to drill a low cross from which Toure opened his body to nonchalantly side-foot a goal fit to mark his 150th appearance for the club.
Dzeko was frustrated with his strike partner when Aguero chose to shoot from an acute angle and Boaz Myhill tipped wide, before Fernandinho volleyed wildly over.
West Brom striker Shane Long was frustrated his penalty claims went unanswered with Kompany and Kolarov in close attendance five minutes into the second half.
Steve Clarke's men displayed renewed purpose throughout the second period and, after Claudio Yacob had clipped Kolarov in the area for Toure to convert, they mounted a belated comeback.
Substitute Matej Vydra got to the byline and Kolarov's miscued clearance struck his own, prone goalkeeper Pantilimon and nestled in the net.
Fellow replacement Anichebe then outmuscled Martin Demichelis and drilled beyond the Romanian from the edge of the area for his first Albion goal, but City had already done enough to claim all three points.
