Julie Blakstad opened the scoring inside the first ten minutes with a simple tap-in from close range, but we had to ride a wave of pressure from the visitors before the half-time whistle blew.
Hayley Raso smashed home our second shortly after the restart to reaffirm our control of the game before Khadija 'Bunny' Shaw's emphatic finish sealed our second win in two Continental Cup games so far.
City settled into the game very quickly, dictating the play from the back as we searched for a route through the Black Cats' defence.
And the crowd didn't have to wait long for a breakthrough as, with eight minutes gone, the ball fell to Filippa Angedahl inside the box from a corner, one-on-one with the Sunderland keeper and the Swede unselfishly squared to Blakstad for an easy tap-in, giving the winger her second goal in as many games.
The two Scandinavians linked up again to almost bag City's second, with Angeldahl once again setting up Blakstad running into the box, but the Norweigan flashed her effort across the face of goal.
However, as the game wore on, Sunderland began to grow into the match and started to threaten City's backline.
Their biggest chance came when, from a corner, defender Brianna Westrup rose highest to win the ball, but directed her header over the bar.
But, after that brief scare, we managed to regain our control of proceedings, and almost doubled our lead when Raso broke quickly down the right wing, firing in a dangerous cross that was just too far in front of either Shaw or Blakstad to connect with.
Another good chance fell to City when Esme Morgan found herself inside the area from right-back, getting her head onto a cross but nodded wide of the Sunderland goal, leaving our advantage at one going into the break.
However, two minutes after the restart, any nerves the crowd may have felt with a one-goal advantage were put to rest as a long-ball forward was latched onto by Raso, who sprinted through on goal before clinically finishing into the back of net.
And two would become three just before the hour mark as a lovely through ball from Steph Houghton found Bunny Shaw, who smashed home beyond Sunderland keeper Claudia Moan to put the result of the afternoon beyond any doubt.
Substitute Ruby Mace almost marked her first game back since returning from injury with a spectacular fourth, but her powerful shot flew just over the crossbar from 25 yards out.
Raso almost capped off her marvelous display with a personal second, finishing from close range, only to be denied by the offside flag.
In the end, we had to settle for three goals as we saw off Sunderland to maintain our 100% record in this season's Continental Cup.
HOW WE LINED UP
Gareth Taylor made six changes from our win over Everton. Ellie Roebuck was brought in between the sticks, whilst Steph Houghton and Alex Greenwood came into the fold to form City's center-back partnership against the Black Cats.
Filippa Angeldahl and Mary Fowler joined Yui Hasegawa in the midfield, whilst Hayley Raso came in on the right wing alongside Khadija 'Bunny' Shaw and Julie Blakstad, who keeps her place following her goal against Everton last week.
Manchester City Women
Starting XI: Roebuck, Morgan (Aleixandri 62'), Houghton (C) (Kennedy 76'), Greenwood, Ouahabi (Stokes 62'), Hasegawa (Mace 62'), Angeldahl, Fowler, Raso, Blakstad, Shaw (Marley-Paraskevas 76').
Substitutes: Keating, Hutchings, Prior, Dahou.
Sunderland AFC Women
Starting XI: Moan, Herron, McCatty, Griffiths, Gears, D. Brown, McInnes, Beer, Dodds (Holmes 68'), Manders (Ede 68'), Westrup.
Substitutes: Jardive, Scarr, J. Brown, Kelly.
Player of the match
A typically electrifying performance from the winger, she proved to be a constant thorn in the Black Cats' side with her speed and trickery.
The game was in the balance following the break with us holding a slender one goal advantage, but Raso came up with the crucial second goal, powerfully finishing into the bottom corner to set us on our way to victory.
WHAT IT MEANS
The win see us maintain our 100% record in the Continental Cup, adding to our 6-0 win over Blackburn Rovers, making it two wins out of two games for Taylor's side.
We still find ourselves second in the group, three points behind Liverpool who have played a game more than us.
Next week, we return to Women's Super League action with Taylor's side tasked with a home encounter against Brighton and Hove Albion.
Kick-off at the Academy Stadium will be at 14:00 GMT on Sunday 4 December.
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