Fell Dane Kevin Magnussen had started in pole but lost the lead after a dramatic moment with Sam Bird midway through the race.
Both drivers cut a chicane and Bird came out in the lead; he then slowed to let Magnussen pass but instead it was Sorensen who came out in front as Magnussen had clouted a kerb.
Sorensen went on to win the race while Carlin driver Magnussen eventually had to retire as he was hit up the back by DAMS' driver Arthur Pic three laps from the end.
ISR rider Sam Bird had to settle for third in the end after Jules Bianchi (Tech 1) took second.
"I took advantage of the battle between Kevin Magnussen and Sam Bird to take the lead," admitted Sorensen.
"I came up behind two cars that had slowed after cutting the chicane, and I had no other choice but to pass and avoid them. It’s an important victory for me and for the team, who are realising the potential shown since the beginning.”