The Seagulls had no answer to the Pilgrims' onslaught as they made it three comfortable home wins in a row on the back of a highly impressive first-half four-goal blitz to overtake their visitors and soar to 16th.
Argyle skipper Paul Wotton was to the fore - smashing home an 11th minute penalty and then crashing in an even more spectacular 21st minute free-kick to make it 3-1.
New striker Nick Chadwick opened the scoring in the ninth minute from 18 yards to claim his first in six starts since joining the Greens for £250,000 from Everton, and he also had a hand in the penalty which put Plymouth 2-1 up as well as starting the move which led to David Norris' 36th minute fourth goal for the home side.
It all started after Guy Butters had a headed effort ruled out for Brighton.
Argyle stormed up the other end and, following a brilliant one-two between Dexter Blackstock, Chadwick struck with a superb rising drive from the edge of the box.
Brighton skipper Charlie Oatway headed the visitors level from a Richard Carpenter free-kick in the 11th minute but seconds later Argyle were back in front.
Seagulls' central defender Adam Hinshelwood handled under pressure from Chadwick and Wotton smashed the ball straight down the middle.
Plymouth carried on piling on the pressure - with Chadwick and central defender Graham Coughlan going close - and it was no surprise when they went further ahead.
Tony Capaldi crossed from the left and Norris was first to the ball. He drifted inside the penalty area, passing a visiting defender before hammering in a left-foot shot to make it 4-1.
Brighton were then reduced to ten men in the 68th minute when Carpenter was red carded for an off-the-ball midfield challenge on Chadwick.
Substitute Scott Taylor scored from close range in the 88th minute to complete Argyle's nap hand.