The Gills beat Yeovil for the first time in seven attempts as Simeon Jackson's spot kick secures the points at a windswept Priestfield.
After Saturday's defeat at Bristol Rovers Mark Stimson switched to a more attacking formation with Simeon Jackson restored to the starting line-up, a tactic that would not take long to pay dividends.
Gillingham went for the jugular direct from the kick-off, Curtis Weston going close with the best of the early action, his scudding effort was pushed to safety by McCarthy at full stretch.
Yeovil's resistance lasted just eight minutes as Febian Brandy was bundled over in the box, allowing Simeon Jackson to deftly chip in his twelfth of the season direct from the penalty spot.
Five minutes later a neat flowing move saw Barcham split the Glovers defence to shreds before a one-two with Brandy presented Jackson with the chance to shoot, though McCarthy was equal to his low drive.
McCarthy was called into action again on 20 minutes to parry Barcham's low strike from the edge of the box after Weston's through ball had played him in but there was nothing he could do moments later as Brandy rattled the crossbar with a wicked angled drive from the right of goal.
Soon after Barcham went close again with a curling effort that flashed wide of the far post prompting Terry Skiverton to change his formation and introduce substitute Sam Williams. It did little to stem the flow of Gills pressure who tested the Glovers custodian again on the half hour with first Brandy drawing a smart save from McCarthy who showed sharp reactions to block Palmer's follow up.
The visitors regrouped after the interval and began the second half with a more attacking approach though a combination of good defending and poor luck in front of goal prevented them from creating a serious chance.
Yeovil threw caution to the wind sending Dean Bowditch on to strengthen their attack on the hour but still the Gills back four remained resolute.
On 64 minutes captain Barry Fuller came within a lick of paint of breaking his duck for the club, curling a cultured free-kick onto McCarthy's left hand upright and watching in horror as it ricocheted to safety.
The Glovers best chance of the half came on 73 minutes as Mason's free kick was nodded back across goal but Royce reacted well to palm Sam Williams close range header over the crossbar.
Ten minutes from time Jean-Paul Kalala got his marching orders for a rash challenge on Kevin Maher leaving the visitors reduced to ten men as Gillingham ground out another vital home victory.
Attendance: 4450 (95 from Yeovil)
Gillingham: Simon Royce, Barry Fuller, Josh Gowling, Matt Fry, Chris Palmer, Mark Bentley, Curtis Weston, Kevin Maher, Andy Barcham, Febian Brandy (Dennis Oli 92), Simeon Jackson
Subs not used: Alan Julian, Stuart Lewis, John Nutter, Mark McCammon, Jack Payne, Luke Rooney
Yeovil Town: Alex McCarthy, Craig Alcock, Stefan Stam, Steven Caulker, Andy Welsh (Dean Bowditch 60), Ryan Mason, Scott Murray (Sam Williams 24), Jean-Paul Kalala, Danny Hutchins, Shaun MacDonald, Jonathan Obika
(Gavin Tomlin 78).
Subs not used: Terrell Forbes, George O'Callaghan, Richard Martin, Nathan Smith.