Nick Heidfeld, who had earned team's first podium finish in Beijing last year, finished eighth but was demoted to P13 following a time penalty after the race.
The first Formula E race to ever take place partially in the wet, the London ePrix was a thrilling spectacle, with many drivers struggling with grip on the wet and bumpy park surface.
Starting in P2, Senna succeeded in building a substantial lead to the car behind to defend his potential podium finish.
Senna defended his position and crossed the line to record his highest ever Formula E result and bring Mahindra Racing their second podium of the season.
"This is a difficult circuit to drive on the limit, especially in mixed weather conditions but we knew we had a set up that would allow us to set a competitive qualifying time and give us the best start in the race.
