The hosting Black Cats pushed hard for an equalising goal as the game wore on, but it was City's Argentine frontman that ultimately proved to be the difference between the two sides at the Stadium of Light.
City, playing their first game since it was announced that Pep Guardiola will replace Manuel Pellegrini as manager in the summer, started in the ascendancy on Wearside and they went close in the ninth minute when a misplaced pass from Sunderland midfielder Yann M'Vila fell to Aguero, but the dynamic frontman fired just wide from 25 yards out.
© Getty Images
However, there were no such problems with Aguero's radar seven minutes later. The home defence failed to clear Jesus Navas's ball into the box and having stepped inside Billy Jones, City's No.10 lashed his shot beyond the reach of Vito Mannone. That goal was the fourth that Aguero has scored in his last three visits to Wearside.
Aguero then saw a deflected effort loop onto the roof of the net, but after that it was the hosts that carved out the better of the chances, thanks mainly to Jeremain Lens.
The Dutch playmaker swung three dangerous crosses into the City penalty area before the break, one of which was met by debutant Lamine Kone. The centre-back's powerful header had Joe Hart well beaten, yet it flew off target.
© Getty Images
Sam Allardyce's charges continued to throw caution to the wind after the restart, while the visiting Citizens found it difficult to retain possession.
Sunderland came closest to scoring an equaliser with 12 minutes remaining when right-back Jones tried his luck from 20 yards out. The ball seemed destined for the top right-hand corner, only for City goalkeeper Hart to turn the danger away with a diving stop and in doing so he preserved the three points for his side.
The victory has seen City tighten their grip on second spot, three points adrift of leaders Leicester City. As for the Wearsiders, they remain 19th and are four points from safety.