Goals from Darryn Stamp and Anthony Elding secured Stevenage victory in a bad-tempered game at Broadhall Way.
Home player Albert Jarrett and Gravesend's Lee Protheroe were sent off for fighting in the second half, provoking an ugly 18-man melee.
But play opened up after the red cards, Stevenage breaking the deadlock with a Stamp header from a Jon Brady cross.
With two minutes remaining, Anthony Elding wrapped up the three points from a flighted Jon Nurse pass.
Stevenage: Julian, Warner, Goodliffe, Hocking (Stamp 69), Henry, Brady, Weatherstone (Bulman 9), Quinn (Elding 56), Jarrett, Nurse, Maamria.
Subs Not Used: Westhead, Flack.
Sent Off: Jarrett (66).
Goals: Stamp 74, Elding 89.
Gravesend: Pullen, Protheroe, Gledhill, Porter, Jackson (Lovell 82), Surey, Saunders, Deane, Drury, Sigere, Pinnock.
Subs Not Used: Wilkerson, Essandoh, Groombridge, Luke Moore.
Sent Off: Protheroe (67).
Booked: Drury, Porter.
Ref: W McIntosh (Lincolnshire).