The former England midfielder, whose short-term move from sister club New York City was extended late on New Year's Eve, came off the bench to settle a remarkable Barclays Premier League game at the Etihad Stadium.
A dull contest burst into life after Yaya Toure broke the deadlock with a stunning strike after 57 minutes.
Four more goals followed in the next 16 minutes as Stevan Jovetic added a second for the hosts and Sunderland hit back through former City players Jack Rodwell and Adam Johnson.
It then fell to Lampard, who had dominated the build-up to the game as his switch from New York was ratified, to make the headlines with a fine headed winner.
It was the former Chelsea player's seventh goal for the club since joining City on what was assumed to have been a loan from New York at the start of the season.
It has now emerged that the 36-year-old was on a short-term contract before moving to Major League Soccer, and manager Manuel Pellegrini will feel the decision to extend the arrangement has immediately been justified.
What unfolded in the second half came in remarkable contrast to the first half.
City, who had Willy Caballero in goal in place of the rested Joe Hart, dominated possession but Sunderland played deep.
City created an early opening with Jovetic flashing a shot wide after combining with David Silva but their opportunities were to be few and far between.
Toure, who gave City control of midfield after being rested for Sunday's draw with Burnley, sliced one chance from distance well wide and high.
After more patient probing, Silva found space to curl in a shot but Costel Pantilimon - Hart's deputy last season - saved well
The Romanian was also in the right place to deal with another Toure shot.
Sunderland's best opportunity of the first half came from a set-piece after they controversially broke from deep while City's Samir Nasri lay injured.
Pablo Zabaleta brought down Jordi Gomez just outside the area and Sebastian Larsson took aim from the free-kick, but Caballero was equal to his effort.
City tried to up the tempo in the second half, and Jesus Navas shot wide within a minute of the restart, but the game appeared to be changing little until Toure finally struck.
City again seemed to be getting little joy as they looked to prise an opening in the Sunderland defence - but Toure opted for power.
The Ivorian - who heads off to the African Nations Cup next week - was lurking just outside the area when he raced onto Jovetic's lay-off and smashed an unstoppable shot into the top corner.
City then seemed to have made the game safe as Jovetic released Gael Clichy down the left and then sprinted into the area to take his return pass and beat Pantilimon with a neat flick.
But with the game having suddenly come to life, Sunderland produced a remarkable response to level with two quickfire goals.
Emanuele Giaccherini extended Caballero with a good shot but Rodwell got a firm header to Larsson's cross from the resulting corner to pull a goal back.
City lost their discipline and were pulled apart moments later as Sunderland attacked again.
Ricardo Alvarez drove the ball across the box and Zabaleta felled Billy Jones attempting to stop the inrushing defender
Johnson made no mistake from the penalty spot.
But after Sunday's frustration against Burnley, when City drew after also surrendering a 2-0 lead, the hosts found another gear.
Typically Lampard provided their inspiration as, just moments after coming off the bench, he arrived in the box at the right time to nod home a Clichy cross.
Lampard might even have had more as he twice forced Pantilimon to save while Navas and Fernandinho were also frustrated by the keeper in an eventful finish.
Source : PA
Source: PA