It was Preston's first win in eight games and first home victory since September 19.
Plymouth had Paul Mariner in charge for the first time, the former Preston coach replacing Paul Sturrock at the helm on Thursday.
Richard Chaplow had a close-range shot deflected behind by the outstretched foot of Plymouth keeper Romain Larrieu and it was from the resulting corner that North End scored.
Ross Wallace's left-wing corner found Chaplow and after a blocked shot, he opened the scoring with a deflected shot from 20 yards that rolled into the bottom left corner of the net.
After 14 minutes, Preston's Michael Tonge was booked for unsporting behaviour.
Jon Parkin hit the bar with a shot and then he headed the rebound straight at the Plymouth keeper after 25 minutes.
A minute later Brown found Wallace and he made it 2-0 into the bottom left corner from 15 yards.
Brown thought it was 3-0 after 37 minutes but this was ruled offside.
Just before half-time, Darcy Blake was shown the yellow card for the Pilgrims.
Andy Lonergan saved from Carl Fletcher, Jamie Mackie and Alan Judge at the start of the second half.
Neil Mellor replaced Parkin and a right foot left wing inswinging corner by Michael Tonge to the near post was saved after 57 minutes.
Judge crossed to Rory Fallon and his shot was saved and Brown's shot from a Callum Davidson cross was saved after 62 minutes.
Eddie Nolan's cross was saved after 65 minutes.
Chris Sedgwick replaced Paul Parry after 69 minutes and Blake's cross was saved two minutes later.
James Paterson and Craig Noone replaced Fallon and Gary Sawyer and Judge had a shot saved after 78 minutes.
Mackie had a shot and Judge had a left-wing corner saved and then man-of-the-match Chaplow was replaced by Veliche Shumulikoski after 84 minutes.