Born in Geneva on 17 April 1986, Grosjean came from a family with a notable sporting heritage — his grandfather Fernand Grosjean was an Olympic alpine skier and his great-grandfather Edgar Brandt was a weapons designer. After dominating French Formula Renault in 2005 with ten wins from sixteen races, Grosjean moved through the Formula 3 Euro Series, winning the championship in 2007 with ASM in a title battle against Sébastien Buemi. He joined the Renault Sport Academy during this period, setting the stage for his graduation to GP2.
Grosjean entered the GP2 Series with ART Grand Prix in 2008, the same year the team fielded him alongside Luca Filippi and Sakon Yamamoto. Despite early setbacks — including a drive-through penalty at the opening round in Barcelona after a disputed defensive move — he showed consistent pace throughout the season. A sprint race victory at Istanbul moved him into championship contention. He ultimately finished fourth in the standings, establishing himself as the highest-placed rookie in that year's field and winning the inaugural GP2 Asia Series with four victories.
When Nico Hülkenberg joined ART for 2009, Grosjean was moved to Barwa Addax (formerly Campos Grand Prix), placed there by Renault. Despite missing the final four rounds of the season — a consequence of his call-up to Formula One to replace Nelson Piquet Jr. at Renault from the European Grand Prix onwards — he still finished fourth in the GP2 standings.
After losing his Formula One seat, Grosjean returned to GP2 mid-season in 2010 with DAMS. He initially replaced Jérôme d'Ambrosio for the German round and later stood in for the injured Ho-Pin Tung from Belgium through to the Abu Dhabi finale. He secured podium finishes in Belgium and Abu Dhabi, finishing fourteenth in the championship despite a partial campaign. In the same year he also won the Auto GP Series title with DAMS, claiming four victories including the decisive race at Monza.
Grosjean's most significant GP2 campaign came in 2011 with DAMS, contesting both the GP2 Asia Series and the main GP2 Series. In Asia, he claimed two pole positions and the championship by six points from Jules Bianchi. In the main series, he won the opening race to immediately lead the standings, then lost the lead to Giedo van der Garde following a disqualification for a technical infringement. He regained the top spot at Monaco, scoring points despite starting from last place. A dominant mid-season run featuring four further victories, including six consecutive podium finishes, allowed him to seal the title at Spa-Francorchamps with one round remaining.
The most controversial moment of Grosjean's GP2 career came during his 2008 stint, when stewards penalised him for a defensive move on Kobayashi at the season opener in Barcelona, turning a likely sprint win into a thirteenth-place finish. In 2011, his disqualification from one round for a technical infringement threatened to cost him the championship mid-season, but he responded with an emphatic run to the title. His Asia Series win over Bianchi in 2011 was notable for the quality of the opposition — Bianchi would go on to earn recognition as one of the brightest talents of his generation.
Grosjean's 2011 GP2 double — the Asia Series followed by the main championship — was the clearest signal that his 2009 Formula One debut with Renault had been an anomaly in difficult circumstances rather than a reflection of his ability. Armed with the championship, he secured a race seat at the newly renamed Lotus F1 Team alongside 2007 World Champion Kimi Räikkönen for 2012, beginning a four-year association with the Enstone squad. His GP2 record demonstrated an ability to regroup after adversity, a quality that would define much of his Formula One career.