Dartford were knocked out of the FA Trophy in dramatic fashion on Tuesday night.
The visitors were cruising to victory in the third qualifying round replay thanks to Dean Cox's brace.
But Dartford pulled one back in the 89th minute through substitute Andre Coker before academy product Taylor Fisher netted a 92nd-minute equaliser.
There was still time, however, for former Darts defender Tom Gardiner to power home the winner in the fifth minute of stoppage time for Eastbourne and set up a home tie with Dorchester in the first round.
It was a grandstand finish that never looked on the cards after Eastbourne ran rings around Dartford throughout the first half.
But, for all their possession and movement, the visitors were unable to find a way through until a minute before the break.
Striker Adam Liddle fired wide from the edge of the box early on before Joel Rollinson failed to properly connect with Dean Cox's cross and keeper Bailey Vose was able to save.
Rollinson's low shot was beaten away before Liddle collected Cox's clever pass and Vose did well to save with his outstretched leg.
Ryan Hall's 20-yard shot was diverted behind for a corner before Eastbourne finally made the breakthrough on the stroke of half-time.
Playing in the hole, Cox found a pocket of space behind the Dartford defence and slotted home into the far corner.
Darts made a double change at the break and marginally improved. Coker added more power down the right wing but there was still a lack of cohesion or quality from the hosts.
It took 64 minutes for an attempt on target but Charlie Sheringham's low drive lacked power.
Eastbourne seemingly wrapped the tie up three minutes later when the impressive Rollinson delivered a perfect right-wing cross and Cox's fine touch and finish doubled the visitors' lead.
Rollinson nearly added a third when Elliot Bradbrook was sold short at the back but Vose was out to make another smart save.
Coker's low drive in the final minute gave Darts some hope before Fisher slotted home the equaliser - only for Gardiner to be left unmarked from a corner to head in the winner.
Dartford: Vose, Onyemah, Wynter, Vint, Greenhalgh (Fisher 79mins), Noble, Philpot (Oyenuga 46mins), Bradbrook, Hayes (Coker 46mins), Johnson, Sheringham. Subs not used: Smoker, Gillies.
Eastbourne: Smith, Adebayo-Rowling, Campbell, Wills, Ransom, Gardiner, Cox (Walker 70mins), West (Torres 60mins), Liddle (Briggs 76mins), Hall, Rollinson. Subs not used: Obudabe, Dawes.