Joe Walsh's early goal proved enough to extend Crawley's unbeaten run to five games by overcoming Oldham.
Welsh got the only goal of the game on seven minutes with a close-range effort after Oldham failed to clear a corner.
The visitors threatened an equaliser through former Crawley striker Charlie MacDonald but he was denied by Red Devils keeper Paul Jones.
MacDonald was unfortunate again after the interval when he headed against the crossbar but Crawley hung on.
VIEW FROM THE DRESSING ROOM
Crawley Town assistant manager Anthony Williams told BBC Sussex:
"We created enough chances to win the game and we ran our luck at times today.
"But that's three points today when for the last two weeks they have been draws. It's a compliment to the way we've been playing and it's pleasing to get the points.
"Oldham are a good side and they worked hard and closed us down and we couldn't play through midfield today as we normally do.
"So there are different ways of winning football games and they've shown we can get clean sheets."
Oldham manager Lee Johnson told BBC Radio Manchester:
"We should have come away with something.
"We've created four of the best chances you'll see and not stuck them in. You'll probably see better finishing from a Sunday league side.
"It was one of those days. Charlie MacDonald has come in and held his hands up because he probably should have had a hat-trick. They had a couple of chances as well but that was when we were going for the game.
"Such is life. We have to dig in deep and come out fighting again next week."