Jack Ross had warned his side before the game that Plymouth were not to be taken lightly.
Argyle were play-off contenders last season and after a woeful start to this campaign, had begun to show signs of life.
For large parts here they exerted immense pressure and threatened to bring an end to Sunderland's winning run.
But a brace from Aiden McGeady and more heroics from Jon McLaughlin secured three more valuable points and moved the Black Cats into the automatic promotion spots.
It is the fifth league win a row, the fourth clean sheet.
Sunderland's resilience and quality in the final third is not in question and momentum is building.
Jack Ross recalled Josh Maja to his starting XI but there was concern when the youngster went down early on, clutching the ankle that has proven troublesome in recent weeks.
He played, on however, and came closer to an opener quarter of an hour in. He collected a pass from the channel and looked to turn at goal, but lost his footing. He still managed to get a shot away from the floor but it was wide.
Minutes later, Chris Maguire launched a long-range effort but Matt Macey was able to turn it wide in the Plymouth goal.
That was the pattern for much of the half, Sunderland enjoying the majority of possession but struggling to carve out real openings in the final third.
They were fortunate, too, 20 minutes when Joel Grant danced past Tom Flanagan in the box, but fired his cross straight at Jon McLaughlin.
The Black Cats threatened only sporadically in the closing stages of the half, Lynden Gooch forcing a save from Macey when his long shot was deflected towards goal.
Defensively they looked secure on the whole, though McLaughlin failed to collect a free-kick on the brink of half-time, Antoni Sarcevic able only to shoot wide.
At the beginning of the second half they looked sharper, and a moment of individual brilliance game them the lead within minutes.
Aiden McGeady, poor in the first half, picked up the ball on the right flank and drove across the box.He delayed the shot for just a moment, taking another touch before firing a brilliant effort across Macey into the bottom corner.
Plymouth rallied strongly, and Dylan McGeouch had to be alert to clear a header from Freddie Ladapo off the line, the in-form striker escaping the attentions of his marker from a corner.
With the Black Cats under pressure, McLaughlin intervened with a double save to rival his efforts at Doncaster Rovers.
Graham Carey looked to have found the top corner with a wicked free-kick before McLaughlin turned it away with his outstretched palm. Moments later, Ladapo turned in the box and the Scotland international did brilliantly to get down and claw it away.
Sunderland were penned in but against the run of play won a penalty.
Luke O'Nien had been on the pitch a matter of moments but as a ball broke loose in the box, he was first to react and fell when Tafari Moore crashed into him.
McGeady stepped up and added his second of the afternoon.
Six minutes of stoppage time tested the away side's nerves but ultimately they were able to see the game out with relative ease.
Sunderland XI: McLaughlin; Matthews, Flanagan, Baldwin, James; Honeyman, McGeouch; McGeady, Maguire (O'Nien, 74), Gooch (; Maja (Sinclair, 72)
Subs: Ruiter, Ozturk, Loovens, Kimpioka
Plymouth Argyle XI: Macey; Moore, Canavan, Songo'o, Grant, C; Ness, Sarcevic, Fox (Lameiras, 72); Carey, Grant, J, Ladapo
Subs: O'Keefe, Dyson, Letheren, Smith-Brown, Grant, P, Jephcott
Bookings: Sarcevic, 48 McGeouch, 60 Flanagan, 61 O'Nien, 84
Attendance: 12,065 (1,305 away)