Plymouth secured their third win in a row at Home Park thanks to Rory Fallon's first-half header.
Fallon met Chris Clarke's corner with a looping header which evaded everybody and found the back of the net.
Jon Parkin almost equalised but Luke Summerfield cleared his header from Ross Wallace's corner off the line.
Billy Jones header another corner just wide and Youl Mawene forced a stunning save from goalkeeper Romain Larrieu in stoppage time as Argyle held on.
Plymouth manager Paul Sturrock: "I thought the back four were immense and our goalkeeper did not have much to do until the very end when he had to make a save.�
"That's three clean sheets in a row at home and after losing at Derby I was delighted to get the result here.
"We have another big home game coming up on Saturday against Ipswich so to get the win tonight was important."
Preston manager Alan Irvine: "I was disappointed not to come away from here with something. I thought we probably deserved something from the game.
"At the end there (Youl) Mawene forced a save from their goalkeeper.
"I could not fault our commitment or work rate, we just lacked that final touch and I thought our final pass went astray, especially in the second half."
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