Dan Ajakaiye and Reece Myles-Meekums both struck in the first half to give the Hornets a 2-0 half-time lead.
The unfortunate Albie Nolan-French put through his own net to triple Horsham’s advantage on the hour, before Chris Dickson wrapped up the win with three minutes remaining.
The Hornets will host Dorking Wanderers in the second qualifying round of the FA Cup on September 14. The two sides met last season in the fourth qualifying round, with the Hornets running out 2-0 winners.
See some of John Lines’ pictures from the game on this page and the ones linked, and read Horsham manager Dominic Di Paola’s thoughts in the West Sussex County Times, out every Thursday.
The Hornets will host Dorking Wanderers in the second qualifying round of the FA Cup on September 14. The two sides met last season in the fourth qualifying round, with the Hornets running out 2-0 winners.