It was a first defeat in eight games for Adam Murray’s side and leaves them fifth – five points behind leaders Worthing.
Jimmy Muitt put Dorking in front before the hosts had George Francomb sent off. But Dorking doubled the lead in first half stoppage time through a Jason Prior penalty.
Courtney Clarke’s superbgoal made it 2-1 early in the second half but as Borough pressed for an equaliser, Brennan Camp made the points safe for Dorking with a late third.
Borough will need to bounce back when they host Weymouth next Saturday.
See pictures from Dorking-Borough on this page and the ones linked and get all the latest from Priory Lane in the Eatbuorne Herald, out on Friday.

1. Lydia Redman
Dorking Wanderers v Eastbourne Borough, National League South Photo: Lydia Redman : Lydia and Nick Redman

2. Lydia Redman
Dorking Wanderers v Eastbourne Borough, National League South Photo: Lydia Redman : Lydia and Nick Redman

3. Lydia Redman
Dorking Wanderers v Eastbourne Borough, National League South Photo: Lydia Redman : Lydia and Nick Redman

4. Lydia Redman
Dorking Wanderers v Eastbourne Borough, National League South Photo: Lydia Redman : Lydia and Nick Redman