The Swiss driver fended off Jean-Eric Vergne in the final stages of the race as the Andretti driver pulled over to the side of the track on the penultimate lap yesterday.
Mahindra Racing's Bruno Senna and Karun Chandhok were sixth and 13th respectively.
Buemi said: "I knew he was going to use his FanBoost, clearly we took it a little bit too safe in the last few laps when he started to catch me because I was still trying to save energy. It's a bit silly right now but that is what it is. Then at the restart I locked the rear wheels twice in the chicane so it was a bit on the edge. I knew he was going to be fast but I don't know what happened to him in the end. I'm really happy with today's result."
He said: "It was a great start, immediate reaction and the car handled very well. On the first lap I attacked the chicane a little bit too hard trying to build a gap and I think I damaged my front suspension. After that it was just trying to maintain really - that's why we were so slow and holding up everybody. I was locking up going into the corners, the car was lifting a little bit - so it was really nerve wracking for many laps until we finally got the pitstop and then the car was back to normal and that's why we had our speed at the end of the race."
Jarno Trulli claimed his first points of the season with a fourth place finish ahead of Alguersuari and Mahindra Racing's Bruno Senna. The Italian driver has endured a tough start in the opening races but believes the team is moving forwards.
There were mixed fortunes for the drivers making their Formula E debut with Andretti driver Jean-Eric Vergne clinching an impressive pole position and fighting for the lead of the race before pulling over with a suspension issue. Amlin Aguri racer and FanBoost winner Salvador Duran had a quiet race in 16th position.
