Johnson saw his Latics team cruise through a vital relegation clash which brought their first win in four games and lifted them out of the npower League One drop zone. The 31-year-old, whose father Gary is boss at Yeovil, was a surprise appointment at Boundary Park and is the Football League's youngest manager.
But his side were far too strong for Hartlepool - who now need a miracle to avoid relegation according to manager John Hughes. Johnson said: "It was a fantastic performance and I've thanked the players for doing everything we asked of them."
He added: "I knew we only had 70 minutes to play at a really high tempo because their fitness isn't quite there at the moment, so our philosophy was to go for it. They put their bodies on the line and to a man they were all fantastic. The positivity of the players was very encouraging and hopefully this result gives us the momentum to push on."
Oldham led after 17 minutes when Jose Baxter's cross was headed home from six yards by Robbie Simpson. Baxter was again the provider 10 minutes later as he crossed from the left and big centre-half Jean Yves Mvoto powered in a 10-yard header.
The outstanding Baxter sealed Oldham's victory in the 70th minute, rifling into the bottom corner from the edge of the box.
Hartlepool created a handful of chances, but Peter Hartley's effort was saved and their finishing let them down. Hughes was left fuming after his side's rotten run stretched to five games without a win or a goal.
Pools are seven points from safety, and Hughes admitted: "This was our cup final but you would never have believed it. We needed to snarl, bite, win tackles and chase every ball, but it didn't happen.
"We need a miracle to stay up now and, if we keep playing like that, we've got no chance. We have given ourselves hope over the last few weeks, so it was bitterly disappointing to see that performance.
"These performances creep in now and again and there was too much acceptance of what was happening. We needed people to wear their heart on their sleeve and win individual battles, but the only leaders were in Oldham shirts. Oldham were hungrier and it was transparent that some of our players didn't want to get into the right areas."