Striker Tommy Mooney produced two clinical pieces of finishing to strengthen Swindon's bid for a play-off place and leave Grimsby facing the threat of being sucked into a relegation battle.
Mooney's 19th and 20th goals of the season in the space of ten first-half minutes were enough to earn Swindon their eighth successive home win as they moved above Brighton and back up to fourth in the table.
Andy King's side have now lost just one of their last 13 matches and the only down side for Swindon was the 86th minute dismissal of midfielder Brian Howard for reckless two-footed lunge on substitute Iain Anderson.
Howard now faces the threat of a three-match ban that could seriously dent Swindon's hopes of challenging for an automatic promotion place.
Captain Matt Hewlett said: "It was an important win for us because we had to bounce back after losing to Plymouth at the weekend.
"There is no reason why we can't go unbeaten until the end of the season and the only disappointing thing is the fact we now face losing Brian for some games after his red card." Mooney put Swindon in command with two goals in the final ten minutes of the first period.
He sent an unstoppable header past goalkeeper Alan Fettis and into the bottom right-hand corner on 35 minutes before adding a second just seconds before the half-time whistle.
Howard's pinpoint pass allowed Mooney to beat Grimsby's offside trap before he calmly beat Fettis much to the delight of the 6,954 crowd.
Howard was unlucky not to add his name to the scoresheet as he twice rattled the crossbar with thunderous drives that had Fettis beaten but Swindon keeper Rhys Evans was also busy at the other end.
He moved smartly to deny Grimsby striker Jonathan Rowan in the 21st minute and did even better 15 minutes later to block an effort from Phil Jevons.
Jevons was certain he had scored when he sent a flying header goalwards from eight yards but Evans somehow clawed the ball away at full stretch to his right.