After a goalless first half, the Hornets broke the deadlock on 68 minutes courtesy of Daniel Ajakaiye.
The goalscorer then turned provider, cutting the ball back for Charlie Hester-Cook to tap home in second half stoppage time.
Horsham will discover who they will face in the next round of the FA Trophy on Monday afternoon.
The Hornets visit Midhurst & Easebourne in the Sussex Senior Cup on Tuesday evening, before welcoming old friends Dorking Wanderers to the Camping World Community Stadium on Saturday [October 14] for a highly-anticipated, and sold out, FA Cup fourth qualifying round clash.
See some of John Lines’ pictures from the game on this page and the ones linked, and read boss Dominic Di Paola’s thoughts in the West Sussex County Times, out every Thursday.
1. Horsham 2, Brightlingsea Regent 0 - in pictures
Action from Horsham's FA Trophy third qualifying round win over Brightlingsea Regent Photo: John Lines
2. Horsham 2, Brightlingsea Regent 0 - in pictures
Action from Horsham's FA Trophy third qualifying round win over Brightlingsea Regent Photo: John Lines
3. Horsham 2, Brightlingsea Regent 0 - in pictures
Action from Horsham's FA Trophy third qualifying round win over Brightlingsea Regent Photo: John Lines
4. Horsham 2, Brightlingsea Regent 0 - in pictures
Action from Horsham's FA Trophy third qualifying round win over Brightlingsea Regent Photo: John Lines