Almost every Formula 1 driver's biography starts with some reference to karting. Not for Robert Doornbos, whose calling to motor sports came relatively late in life, when he visited the Belgian GP as a 16 year old. It quickly turned out that he had talent, however, when he started competing in Formula Opel and finished runner up. This success was sufficient for him to make the step to Formula Ford and later to Formula 3. In 2004 he became the rookie of the year in F3000 with a win at Spa, which landed him a test driver contract at Jordan. In 2005 he managed to grab Patrick Friesacher's seat at Minardi when the Austrian's sponsor money ran out. While his qualifying performance against fellow Dutchman Christijan Albert was decent, given he joined the team at a late stage in the season, his best race result was a 13th place in Turkey and at Spa. Doornbos stayed in Formula 1 after Minardi disappeared, racing for the Red Bull team first as a test driver, later as a replacement for Austrian Christian Klien.
While he outpaced veteran David Coulthard at his first qualifying for Red Bull at the Chinese GP, he was not able to improve significantly on the results achieved with Minardi during the race, coming in 12th in China and Brazil and 13th in Japan. He stayed on with Red Bull as a test driver for 2007, also carrying out publicity stunts such as racing across the 30 km long causeway "Afsluitdijk" in the Netherlands. At the same time, however, he found himself behind the wheel of a "Minardi" again, having joined Paul Stoddart's ChampCar (CART) outfit Minardi Team USA in the United States. Doornbos did incredibly well, winning two races and finishing on the podium several times to come in third in the 2007 championship, also being crowned rookie of the year.
When Champcar and Indycar merged at the end of 2007, Stoddart left the series and Doornbos had to look for a drive elsewhere. In the final years of his active career, Doornbos raced in Superleague Formula, winning two races, and in Indycar where he struggled to make a dent.