A brace from Joe Garner - making it 20 goals for the season - and a rare Keith Keane goal gave North End the three points in Greater Manchester.
North End took the lead within the opening five minutes, Keane flicking Humphrey’s left foot shot past Mark Oxley into the bottom left hand corner.
Joe Garner made it two with a close range strike from another Chris Humphrey assist after the break, but Gary Harkins reduced the arrears before Latics sub Jonson Clarke-Harris was sent off for handling on the line.
Joe Garner saw the resulting penalty saved, but fired in from the edge of the box to secure the Lilywhites’ first win at Boundary Park since August 1999.
Manager Simon Grayson was without Aussie centre half Bailey Wright for the first time this season, the No.6 ruled out through injury, Jack King replacing him at the heart of the defence in an otherwise unchanged line-up from the one that overcame Walsall seven days previously.
And it was King who created the opening goal with his initial pass. He read a Latics through ball and stepped out, looping a quick pass straight out to Chris Humphrey on the right hand side. The Jamaican international’s first touch was superb, bringing the ball under control and cutting inside his full back before firing a left foot shot goalwards. Skipper Keith Keane had burst from the middle of the park and flicked a knee at the No.7’s shot and it directed the ball perfectly into the bottom left hand corner past the Oldham skipper.
The Lilywhites were backed by almost 3,000 away fans, who went beserk at the early start and never stopped singing for the following 90 minutes.
However, the home side reacted quickly, playing their brand of attractive passing football, but their first real chance came not from this expansive game, but from a North End mistake as Danny Philliskirk fired a foot wide of the right hand post after former Oldham man Neil Kilkenny failed to clear a ball into the box from the right wing.
Just before the 20 minute mark, another ex-Latic, Craig Davies lost the ball on the edge of the home side's box, but tracked back to win it and laid it off to Paul Gallagher, who in turn fizzed a 25 yard drive a foot wide of the left hand post with the keeper beaten.
At the mid-point of the half Jack King was at it again; the centre half played a wonderful pass out of the defence to Gallagher, who then played a one-two with Humphrey, but Grounds did well to nip in and concede a corner.
Seven minutes before the break a Keane shot flicked off the head of Grounds which went out for corner after Gallagher won ball back off his full back. From the ball back in from Gallagher, a Tom Clarke header was claimed by Oxley.
A good save by Declan Rudd just before the hour mark kept out a header from Oldham centre half Adam Lockwood, after a right wing cross from full back Connor Brown.
And an even better save from the North End custodian came on 64 minutes; a one handed palm out from Latics skipper Korey Smith’s 25-yard pile-driver denied them an equaliser, with Jack King cleaning up afterwards.
And with 19 minutes to go it was 2-0 to the Lilywhites. Their best piece of play of the second half saw David Mellor outstripped by Chris Humphrey on the right, driving to the byline and pulling the ball across to the goal line, where top scorer Joe Garner was on hand to slide in from a yard out to double the lead.
Straight up the other end, Declan Rudd was needed again, this time to keep out an excellent strike from David Worrall, whose left foot drive from 20 yards had to be tipped round the post.
The deficit was halved with 15 minutes to go as Scot Gary Harkins hooked an excellent volley into the top right hand corner from the left hand corner of the box, after the Lilywhites failed to clear substitute Jonson Clarke-Harris’ ball in from the left.
Two minutes later North End thought they had scored a third as Joe Garner met another brilliant Chris Humphrey cross from the right. But it wasn’t given, however, a penalty was as Jonson Clarke-Harris handled it on the line and was given an immediate red card by match official Stephen Martin.
Joe Garner had the chance to make it 3-1 with the spot kick, but his right footed drive towards the top left corner was brilliantly tipped away by Mark Oxley to deny the front man his 20th goal of the season.
Josh Brownhill came on and was inches away from making it 3-1 with his first touch, Beavon, also on from the bench, fed Garner from the right and he in turn threaded it through to Brownhill, who was onside, but slid the ball past the keeper and past the left hand post.
Chris Humphrey also had a chance for a third as Gallagher spread the ball to him on the right hand corner of the box, in space, but he got caught in two minds as whether to shoot or cross and in the end did neither as the ball drifted over for a goal kick.
But, Garner wasn’t to be denied his 20th of the season, as with three minutes to go he, Humphrey and Scott Wiseman broke with pace and the centre half for the day and No.32 laid the ball across into the path of the top scorer, who controlled, stepped inside his defender and fired a shot off both posts and eventually into the bottom right hand corner.
Garner became the first PNE striker to hit 20 goals in a season since Richard Cresswell in the 2004/05 Play-Off Final season.
The Lilywhites bossed the possession and chances after the third and Josh Brownhill and Stuart Beavon both went close to adding a fourth, but it finished 3-1 with North End’s first win in Oldham for 15 years.
Oldham Athletic line-up: Oxley, Brown, Grounds, Wesolowski, Smith, MacDonald (Turner, 80), Mellor, Lockwood, Philliskirk (Clarke-Harris, 58), Worrall (Kissock, 79), Harkins. Subs not used: Dunfield, Winchester, Wilson, Rachubka.
PNE line-up: Rudd, Keane, Laird, Clarek, Humphrey, Gallagher, Garner (K Davies, 87), C Davies (Beavon, 81), King, Wiseman, Kilkenny (Brownhill, 82). Subs not used: Stuckmann, Hume, Buchanan, Holmes.
Attendance: 6,698 (2,922 away fans)
Referee: Mr S Martin