Petrov grew up in Vyborg and, unlike most contemporary racing drivers, bypassed karting entirely. He began competing in rally sprints and ice races in 1998 before moving into the Russian Lada Cup in 2001, where he dominated the 2002 season by winning every round to claim the maximum 500 points.
He transitioned to European single-seaters in 2003, racing in Italian Formula Renault and making early appearances in the Eurocup Formula Renault 2.0. After a season focusing on the Russian Lada Revolution championship in 2004, he moved to the Euroseries 3000 in 2006, finishing third in the standings with four wins.
Petrov spent three seasons in the GP2 Series with Campos Grand Prix (later Barwa Addax). He claimed his best GP2 season in 2009, finishing runner-up to Nico Hülkenberg with two wins at Istanbul and Valencia Street Circuit.
Petrov signed with Renault for 2010 alongside Robert Kubica, becoming the first Russian driver in Formula One World Championship history. His breakthrough result came at the 2010 Hungarian Grand Prix, where he qualified seventh and finished fifth ahead of the more experienced Kubica. He also contributed to the title narrative at the season-ending Abu Dhabi Grand Prix: running ahead of Fernando Alonso and Mark Webber after strategy played out, he held position to the flag, effectively preventing both title challengers from overtaking Sebastian Vettel and securing the championship for the German.
In 2011, with Kubica sidelined by a serious rallying injury and replaced by Nick Heidfeld, Petrov achieved the highlight of his career. At the opening Australian Grand Prix he qualified sixth and finished third — his only Formula One podium — behind Sebastian Vettel and Lewis Hamilton. He earned several more points finishes during the year, but was dropped from the team at the end of 2011 when Romain Grosjean was signed alongside Kimi Räikkönen.
Petrov moved to Caterham for 2012, replacing Jarno Trulli and partnering Heikki Kovalainen. The season was one of survival: Caterham consistently outpaced the Marussia and HRT cars but could not reach the midfield. His best result was a 16th-place finish in Malaysia, which he equalled at Bahrain. A notable moment came at the European Grand Prix in Valencia, where Petrov ran as high as tenth during the race — a result that would have earned Caterham their first Formula One point — before a collision with Daniel Ricciardo dropped him to thirteenth. In the season finale in Brazil, his 11th-place finish helped Caterham leapfrog Marussia to tenth in the Constructors' Championship, worth significantly more prize money. Caterham did not renew his contract for 2013.
After Formula One, Petrov signed with Mercedes for a season in the Deutsche Tourenwagen Masters (DTM), finishing last in the standings without points. He subsequently competed in FIA World Endurance Championship events and, as of 2025, was competing in the Middle East Trophy for SMP Racing.
Petrov is widely known in Russia by the nickname the "Vyborg Rocket." He voiced a character based on himself in the Russian-language release of the 2011 Pixar film Cars 2. His father Aleksandr was a prominent businessman and municipal deputy in Vyborg before his assassination in 2020, a tragedy that required Petrov to stand down from a temporary steward role at the 2020 Portuguese Grand Prix.