Andy Clarke was hailed as the hero as he came off the substitute's bench to score Peterborough's first home goal of the season.
Posh had picked up just one point from their previous four matches at London Road but Clarke set them on their way to all three points against Plymouth with a sweet volley 12 minutes after half time, after Jason Lee had flicked on a Marc Joseph throw at the near post.
Veteran forward Clarke was called upon by boss Barry Fry to fill in for the injured Helgi Danielsson in an unaccustomed central midfield position, and Fry was thrilled that the change paid off.
He beamed: "We wanted Andy to burst in from a deeper area and thankfully it worked. I'm so pleased for my players because this win has been a long time coming and nobody can deny that they deserved it.
"I was also pleased for the supporters who were behind the team from start to finish even though we hadn't scored in seven games."
Francis Green sealed the win five minutes from time with his second of the campaign - tapping into an open net once Adam Newton had jiggled his way into the penalty area and laid an inviting ball into his path.
High-flying Plymouth were dangerous on the break throughout the clash and David Beresford was unlucky to see a long-range effort drag wide.
Paul Wotton did go close with a 30-yard free-kick shortly after Clarke's opener but the night belonged to Peterborough - who had been ready to face further frustration when Joseph had a first-half header cleared off the line, and David Farrell saw a half-volley clip the crossbar.
Argyle manager Paul Sturrock admitted Posh were worthy winners.
He said: "Peterborough deserved the three points simply because they were better than us on the night. We were very slack at times and the work needs to be done on the training ground."