Lee Holmes scored one goal and set up another as Preston eased their relegation worries with a welcome win.
Holmes netted for just the second time this season when he curled in from 20 yards before crossing for Will Hayhurst to guide home the second.
Preston could have extended their lead but Jack King shot over from six yards.
Stevenage improved after the break but Robin Shroot fired over from inside the box before fellow substitute Steve Beleck headed wide.
It meant struggling Stevenage were condemned to a fifth consecutive away defeat as Preston moved seven points above the relegation zone.
VIEW FROM THE DRESSING ROOM
Stevenage manager Gary Smith told BBC Three Counties Radio:
"I thought we looked flat from the opening stages.
"We found it extremely difficult to get ourselves any sort of foothold in the game.
"Today we were second best for too long and they won the game in that period.
"It's now time for the players to really stand up and be counted. .I expect there will be a reaction on Tuesday [against Bournemouth]."