The Spaniard scored in the 90th minute to earn the hosts a stunning late victory over their Premier League title rivals at Stamford Bridge
The match had been heading towards a draw after Sergio Aguero canceled out Andre Schurrle’s opener but the 90th-minute strike for Torres, who had earlier hit the crossbar, means the Blues move up to second in the table.
Gary Cahill and the Spain striker had spurned golden opportunities in the first half before the latter laid on Andre Schurrle to score his first Chelsea goal and give Jose Mourinho’s men a deserved halftime lead.
Sergio Aguero’s thunderous strike – his sixth goal in four outings and 10th of the season – left Petr Cech grasping at thin air three minutes after the restart and the equalizer prompted a sustained spell of City pressure.
Manuel Pellegrini's team appeared the most likely winner heading into the closing stages, but as they pressed, Chelsea substitute Willian launched a hopeful ball forward and caused a horrific moment for defender Matija Nastasic and goalkeeper Joe Hart.
Nastasic headed back towards his own goal, only to see the on-rushing Hart miss the ball to leave Torres with a simple finish for the winner.
Ashley Cole returned to displace Cesar Azpilicueta in Jose Mourinho's only change to the Chelsea XI that beat Schalke 3-0 in the Champions League in midweek.
Vincent Kompany’s continued injury absence with a thigh complaint meant that City boss Manuel Pellegrini handed Martin Demichelis a debut at center back and pushed Javi Garcia into a holding role to match Chelsea's three-man central midfield.
The reshaped heart of the visitors’ defense was found wanting in the third minute as a corner was partially cleared and Oscar found Gary Cahill, who blazed over when unmarked at the back post.
City proceeded to dominate possession in the first quarter of the match without fashioning a clear chance and the club offered up another for the hosts in the 29th minute.
For a second time, City's backline was virtually non-existent as Torres ghosted onto Ramires' pass, only to fire over with the goal at his mercy.
The striker atoned for his error three minutes later, though, with an electric burst of pace to beat Gael Clichy and cross for Schurrle to enjoy a simple finish.
A seemingly rejuvenated Torres subsequently tormented City's other fullback, Pablo Zabaleta - cutting in past the Argentina international and his countryman Demichelis to rattle Joe Hart's crossbar with a superb curling effort.
Petr Cech then beat away a rasping shot on the turn from Aguero in the 42nd minute as City pressed for a way back into the game.
But Cech could do nothing four minutes after the break when the in-form striker made light of an acute angle to drill Samir Nasri's throughball into the top corner.
Chelsea was suddenly reeling and Cech gratefully grasped Garcia's free header from David Silva's free kick after Ramires had become the fourth player into referee Howard Webb's notebook for hauling down Nasri.
From similar situations at the other end, Torres and John Terry passed up opportunities from Frank Lampard deliveries and, by the time Cech's left boot had denied Silva in the 65th minute, the contest was wide open.
Aguero searched for another inspired intervention as he lobbed over the far corner following a lightning-quick break involving Silva and substitute Jesus Navas, but it was Torres - and the unfortunate Hart - who were to have the final say.