Lee Cattermole's fifth goal of the season helped Sunderland keep the pressure on the League One top two.
The Black Cats dominated the first half against a side in fine form, and while they were occasionally under pressure in the second, George Honeyman's late goal sealed a deserved win.
It was the third consecutive league win for Jack Ross and his side who are building some encouraging momentum at a vital stage of the season.
Barnsley had put the Black Cats under pressure with a remarkable 3-0 win in the early kick-off, playing for over an hour with ten men.
But Sunderland looked in good shape right from the off, with Jack Ross bringing Lewis Morgan into his starting XI.
After a wonderful cameo at Bristol Rovers, the Celtic loanee looked in the mood and had an early effort deflected over the bar.
Plymouth had been given a boost pre-match with top scorer Freddie Ladapo declared fit to play. He went close with ten minutes on the clock from the edge of the area, Jon McLaughlin seemingly doing well to turn his effort wide, despite the referee giving a goal kick.
That, though, was the in-form side's only effort of a half in which they were absolutely dominated by an excellent Sunderland side.
Bolstered by the continuing steel of Lee Cattermole and Grant Leadbitter in midfield, the gameplan was to get the ball wide early and allow Morgan and Aiden McGeady to take on their marker.
The early results wee encouraging, a number of good deliveries just turned away by the away defence.
The pressure continued to rise, however, with Derek Adams increasingly concerned as they continued to cough up possession.
An error finally put Sunderland ahead on the half hour mark.
Morgan did well to pinch the ball off a defender in the box, cutting a low cross into a dangerous areas as he had done right through the half.
The onrushing Lee cattermole gathered and composed himself, firing a fine effort into the roof of the net.
The home side continued to open up their opponents, with excellent crosses from the overlapping Luke O'Nien and Reece James just evading their target.
On the stroke of half time they twice went close to the crucial second goal.
Morgan released McGeady with a superb through ball, catching the away defence completely off guard. McGeady raced clear but was denied by Kyle Letheren as he took aim for a tight angle.
Letheren did superbly to block again moments later when McGeady got to the byline and found Will Grigg, who turned his marker and struck an effort at goal
The interval gave Plymouth a chance to regroup and they started the second half well, Oscar Threlkeld firing a volley over the bar from the edge of the area.
They were left incensed when the referee then turned away their shout for a penalty, the visitors alleging that Tom Flanagan had used his arm to block an effort from Gary Sawyer.
The game was now swinging from end to end, McGeady heading over at the back post after a good cross from O'Nien.
Right-back Ashley Smith-Brown then went within inches of stunning the home support, his long-range effort on is weaker foot beating McLaughlin but drifting just wide.
McLaughlin made a smart stop as shot from the edge of the area was deflected towards goal, Threlkeld somehow missing the target as the rebound fell for him at the back post.
Ross acted by bringing Duncan Watmore on for Morgan, moving George Honeyman into the wide areas where they were struggling.
Sunderland steadied, and nearly had a second when Reece James struck a brilliant first time cross into the box, Grigg's looping header drifting wide.
Adams went for broke, sacrificing a midfielder for striker Ryan Taylor.
In truth the move benefited Sunderland, who wee able to reassert some control in the middle of the pitch.
With minutes to go they were able to kill it off, McGeady dancing down the left wing and beating his man with a wonderful piece of skill. He then stood up a good cross to the centre of the box, where Watmore teed up Honeyman.
The captain thumped home an excellent finish to make it three wins on the bounce and keep up the pressure on the top two.
Sunderland XI: McLaughlin; O'Nien, Flanagan, Dunne, James; Leadbitter, Cattermole, Honeyman; Morgan (Watmore, 66), McGeady (Gooch, 90), Grigg (Wyke, 90)
Subs: Ruiter, Matthews, Ozturk, Power, Wyke, Gooch
Plymouth XI: Letheren (Macey, 79); Smith-Brown, Edwards, Canavan, Sawyer; Threlkeld (Taylor, 70), Fox, Songo'o; Carey, Lameiras (Anderson, 79), Ladapo
Subs: Riley, Ness, Jones, Wootton
Bookings: Dunne, 49 Edwards, 90