The impressive Seagulls took a 22nd-minute lead after a foul by recalled right-back Marcel Seip on Marcos Painter. Elliott Bennett's free-kick from the left was whipped in to the near post and helped on by Tommy Elphick past home keeper Romain Larrieu.
Bennett was also provider - from another free-kick - as visiting skipper Inigo Calderon forced a goal-line stop from Larrieu in the 35th minute. The ball was scrambled clear but the relief was short-lived as former Plymouth striker Ashley Barnes, who joined the Seagulls from Argyle in summer, swooped to steer home a Bennett cut back from the by-line in the 43rd minute.
Argyle had the better chances in the early spell with in-form winger Craig Noone flashing the ball across the face of goal with a pacy left-wing cross in the 18th minute. Two minutes later, from the right wing, Noone sent a dipping drive just over.
At the start of the second half home boss Peter Reid introduced attacker Joe Mason for full back Onismor Bhasera.
Argyle did their best to reduce the arrears with Rory Patterson sending a 25-yard free-kick just wide and striker Bradley Wright-Phillips crashing an angled shot into the sidenetting.