Further back, freshly-crowned drivers' champion Davide Valsecchi and team-mate Felipe Nasr secured the DAMS squad's first teams' title in GP2 with fifth and seventh placed finishes - enough to beat rival Lotus.
Polesitter van der Garde leapt away at the start, holding off fellow front-row man Marcus Ericsson of iSport, with series runner-up Luiz Razia (Arden) jumping up to third as Nasr made a poor start, dropping from third to ninth.
The race was interrupted by the safety car on lap nine, as Rene Binder spun his Lazarus machine at the final corner.
His team-mate Sergio Canamasas, running seventh, was also causing trouble: his mechanics worked on his car too close to the start of the formation lap, and a drive-through penalty for this became a black flag.
Even then, he continued racing as his radio wasn't working and he wasn't looking at his pitboard. It took a car problem for him to actually pit, where he was admonished by his team.
At the front, meanwhile, van der Garde stroked it home from the restart, winning comfortably by 1.7s.
"We deserved that," he said. "We started off the season not so good, and we've had the pace but not the luck in the last few races."
Ericsson finished a clear second: "It was a tough race, and Giedo was so quick in the beginning," he said. "I struggled towards the end, maybe I shouldn't have chased him to hard early on because of the safety car."
Third place swapped hands on the final lap, as Racing Engineering's Fabio Leimer scrabbled past a tyre-troubled Razia on the run to Turn 10.
Two laps earlier, they had both straightlined the Turn 10 chicane, so intense was their duel. "I could see his rear tyres were struggling, and I just managed to get past," said Leimer.
Razia just held off Valsecchi for fourth, while Lotus's Esteban Gutierrez, who did brilliantly to nurse his set of supersoft tyres for a race distance, just held off Nasr, who had passed Stefano Coletti for seventh with a handful of laps remaining.
Gutierrez was confirmed as third in points, ahead of Saturday's racewinner winner Max Chilton, who slumped from eighth to 19th on his supersoft rubber.
Johnny Cecotto Jr just missed out on a point after a charging drive from last to ninth, having pitted for supersoft tyres and been given a drive-through for putting Jolyon Palmer into the wall early on.
The unwell James Calado also starred, finishing 10th from 18th despite suffering food poisoning.
And in the nine-year history of GP2, it was the final race in the category for Scuderia Coloni. With Luca Filippi unable to start, Fabio Onidi finished down in 20th.