The 34-year-old left-back launched a clearance from well inside his own half and was amazed to see it bounce over the head of hapless keeper Scott Flinders.
The goal, scored 12 seconds after the restart for the second half, was Oldham's third and effectively sealed an impressive victory.
Oldham produced an excellent display as their revival under manager John Sheridan continued as they made it 10 points from a possible 12.
But the upturn in the Gills' fortune came to a juddering halt at Boundary Park as their run of three straight wins came to an end.
Oldham could not have made a better start taking the lead in the fourth minute after the Gills failed to clear a corner.
Andy Liddell's overhead kick sailed over the defence and Will Haining bravely shot into the roof of the net from eight yards.
And midway through the opening half Oldham doubled their advantage when Paul Warne broke on the right and Richie Wellens played in striker Chris Porter who slotted home a low shot from the edge of the penalty area.
Indeed, Oldham should have gone on to build a far greater lead than 2-0 as a number of other clear-cut chances went begging in a one-sided opening period.
Porter could have easily completed a first-half hat-trick while midfield player Gary McDonald failed to convert a couple of decent openings.
Charlton's spectacular goal gave Oldham what appeared an unassailable 3-0 lead.
But almost immediately Gills pulled a goal back when Neal Eardley was harshly adjudged to have brought down Gary Mulligan allowing Michael Flynn to score from the spot.
Oldham felt aggrieved as in the first half they had two penalty shouts of their own turned down.
Oldham ought to have added to their tally in the last half hour as they carved out a number of decent chances as Warne, McDonald, Eardley and substitute Craig Rocastle all went close.
Then in stoppage time Porter scored his second and fifth goal in his last three games as he swept home low shot following a great pull-back from McDonald as Oldham finished on a high note.