The striker, helped back to fitness by a loan spell at AFC Portchester, converted an early penalty as the lower division Stags progressed to the quarter-finals with a 2-1 victory at Privett Park.
It was a deserved victory for a Totton side who are flying high in second place in Division 1 South of the Southern League, helped by a stunning away record.
Pennery put the visitors on the road to victory in the seventh minute after left-back Harvey Rew had brought down Shaquille Gwengwe.
Pennery struck his penalty low to Ellis Grant’s right, but even though he got a hand to it he couldn’t keep the shot out.
Gosport levelled midway through the half when striker Matt Paterson rose above keeper Lewis Noice to finish off a nice passing move with a header from six yards out.
But Totton always looked the more dangerous side going forward and they claimed the latest in a series of impressive away wins with a 56th minute decider.
Jordan Ngalo received the ball on the left flank and jinked inside to fire in an angled shot which took a slight deflection as it flew past Grant and nestled in the far corner.
Totton have played 10 of their 15 league games away from home this season and have won seven of them. Included in that run are TWO 8-1 wins - at Cinderford and Barnstaple - a 5-0 romp at Mangotsfield, a 4-0 win at Lymington and a 4-1 success at Willand Rovers. That is some record, to say the least.
They also recently travelled to Hawks’ National League South rivals Concord Rangers and dished out a remarkable 5-0 hammering to their two divisions higher hosts.
Only four of the Stags side that started against Concord also started at Privett Park - Ngalo, captain Harry Medway, defender Ade Olumuyiwa and midfielder Adam Tomasso, who also recently had a loan spell at Portchester.
But it was still easy to see why Totton have scored so many goals this season as their much-changed side looked far sharper and quicker than Gosport early on. Though it was not Boro’s first choice Southern League Premier South XI, it was still an experienced team full of first teamers.
Both sides were forced into early changes after Pennery’s spot-kick - Boro captain Mike Carter going off to be replaced by Jake Wright and Gwengwe replaced by Sam Griffin.
Griffin was to enjoy a huge amount of space on the right side, while on the other flank pacy left-back Jordan Raguette - a former Gosport player - was one of the visitors’ most impressive performers.
Gosport boss Shaun Gale handed teenage centre half Finn Walsh-Smith a first team debut early in the second half, replacing Matt Briggs, and there was a rare chance for ex-Bromley U23s midfielder Paul Agbesyi to impress when he came on.
Pennery looked a handful for the Boro defence throughout and got some well-deserved applause from the visiting fans when he made way for Ethan Taylor – briefly a Gosport player under Lee Molyneaux in 2019/20 – on 73 minutes.
In truth, Gosport didn’t create too much from open play throughout the game and it wasn’t until the closing minutes that they looked capable of a second equaliser.
Brad Lethbridge was able to turn onto an Elliott Wheeler pass on 86 minutes, but thumped his shot from the edge of the penalty box over the crossbar.
Then, three minutes later, Theo Lewis had Boro’s best chance of the half, Noice saving from close range following a Wheeler cross. It was virtually the only shot Noice had to save all evening, not that Grant had too many saves to make either with Brett Williams firing a couple of efforts high and wide.
Totton, though, were worthy winners and could even afford to leave 11-goal top league scorer Hisham Kasimu on the bench.
Gosport: Grant, Rew, Kavanagh, Casey, Briggs, Gomis, Wheeler, Carter, Lewis, Paterson, Lethbridge. Subs used: Wright, Walsh-Smith, Agbeysi.
Totton: Noice, Waterfield, Raguette, Medway, Olumuyiwa, Tomasso, Read, Ngalo, Williams, Pennery, Gwengwe. Subs used: Griffin, Baughan, Taylor.