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 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.
"I knew we only had 70 minutes to play at a really high tempo because their fitness isn't quite there are 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."
Robbie Simpson nodded home the opener before big centre-half Jean Yves Mvoto powered home a header of his own soon after to put Oldham in first-half control, with the outstanding Jose Baxter, who had provided both the earlier assists, sealing victory in the 70th minute.
Johnson added: "The fans gave me a nice reception and it's a great way to start, although it felt weird to be a manager instead of a player and there were times when I wanted to go for headers.
"The way we played and pressured Hartlepool meant we could free up Jose Baxter, who was a genius. It isn't just the result that I'm delighted with, it's also the way we achieved it."