Reece Myles-Meekums gave the Hornets the lead on 39 minutes before Charlie Hester-Cook’s fine driven strike doubled the advantage on 48 minutes.
Lucas Rodrigues was brought down in the area in second half stoppage time, and James Hammond duly converted the penalty.
The win leaves Horsham fifth in the Isthmian Premier, seven points behind third-placed Dartford with two games in hand.
The Hornets continue their Sussex Senior Cup title defence at National League South outfit Worthing on Tuesday evening (7.45pm kick-off).
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.
1. Horsham FC see off Carshalton for fifth win in a row – the match in pictures
Horsham FC’s emphatic 3-0 home win over Carshalton Athletic saw them notch their fifth Isthmian Premier win in a row. Photo: John Lines
2. Horsham FC see off Carshalton for fifth win in a row – the match in pictures
Horsham FC’s emphatic 3-0 home win over Carshalton Athletic saw them notch their fifth Isthmian Premier win in a row. Photo: John Lines
3. Horsham FC see off Carshalton for fifth win in a row – the match in pictures
Horsham FC’s emphatic 3-0 home win over Carshalton Athletic saw them notch their fifth Isthmian Premier win in a row. Photo: John Lines
4. Horsham FC see off Carshalton for fifth win in a row – the match in pictures
Horsham FC’s emphatic 3-0 home win over Carshalton Athletic saw them notch their fifth Isthmian Premier win in a row. Photo: John Lines