Manchester City had looked set to join neighbours United and Everton as the only teams to have taken points off the champions until Cole's intervention.
Though Cole's sixth goal of the season was a scrappy effort, it was enough to ensure Chelsea took another massive step towards defending their Premiership title.
The importance of the victory was underlined by manager Jose Mourinho's clenched-fist celebration at the final whistle, as it was City who 14 months earlier had inflicted Chelsea's only league defeat of last season.
The Blues were forced to make a late change when Frank Lampard pulled out through a virus.
The England midfield player, who had made 164 consecutive appearances since September 2001, withdrew having taken part in the pre-match warm up.
Lampard was replaced by Eidur Gudjohnsen, with Paulo Ferreira winning a late call up to the bench.
Chelsea clearly missed the midfield drive of Lampard in a disappointing opening half.
City, who recalled Andrew Cole and Richard Dunne, were also without an influential midfield player, with Claudio Reyna ruled out through injury.
Joey Barton had the best chance of the opening period when, after 15 minutes, he saw a well-struck shot saved by the legs of Petr Cech after a neat cut back from Trevor Sinclair.
City keeper David James was a mere spectator and his only moments of anxiety came from his own team-mates' failings.
Midway through the half a long ball over the defence left Didier Drogba in the clear in front of goal.
The Ivory Coast striker went down following a challenge from James, but Chelsea's appeals for a penalty were waved aside by referee Uriah Rennie.
Then, in injury-time, Dunne's wayward header let in Drogba, but his lob over the City keeper flew wide of the target.
John Terry and Drogba had decent efforts at goal early in the second half, but Chelsea struggled to make inroads against a well-marshalled City defence.
And just short of the hour Mourinho made a double substitution, replacing Drogba and Damien Duff with Hernan Crespo and Arjen Robben.
The visitors began to carry more of a threat, with Robben's angled shot well kept out by James.
And the two Chelsea substitutes combined with Gudjohnsen to set up Cole's points-clinching goal in the 79th minute.
Robben broke on the right and slipped the ball inside to the Icelander, whose deflected shot James did well to claw away.
Unfortunately for the City keeper, Crespo was on hand to touch the ball sideways to Cole, who squeezed in his shot at the far post from inside the six-yard box.