Friesacher began racing motocross at the age of five before switching to karting in 1990 after watching an event at the A1-Ring. He became the first Red Bull junior driver in 1994. A serious crash at Schwarzlhalle in 1997 left him with severe leg injuries that required six weeks of hospitalisation and seven weeks in a wheelchair, forcing him to relearn how to walk.
After recovering, Friesacher progressed through French Formula Campus (third in 1998) and French Formula 3's B class (third in 1999), before moving to German Formula 3 in 2000 and recording two wins at Sachsenring and Oschersleben to finish sixth in the standings.
Friesacher stepped up to International Formula 3000 in 2001 with the Red Bull Junior team, scoring three top-six finishes to place thirteenth overall. He stayed with Red Bull for 2002, earning his maiden podium at Monaco and rising to tenth in the championship.
In 2003 he achieved his breakthrough season, finishing fifth and claiming victory at the Hungarian round — a result made more remarkable by the fact that he had returned from a broken arm sustained earlier in the year. For 2004 he joined Super Nova but switched to Coloni after four races; he again finished fifth in the standings and added a second win at the Hungaroring.
At the end of 2004, Red Bull dropped Friesacher after he declined a move to Formula Nippon.
His Formula 3000 victories attracted the attention of Minardi principal Paul Stoddart, who gave Friesacher a test at Misano in November 2004. The Austrian set the fastest time of the day, convincing Stoddart to sign him for the 2005 season after the original planned driver Nicolas Kiesa failed to secure sponsorship.
Friesacher drove the opening eight rounds of the 2005 Formula One World Championship for Minardi. Highlights were limited: at Monaco he qualified thirteenth, his highest grid position in F1, and outpaced both Albers and the Jordan drivers. At the 2005 United States Grand Prix — which famously saw only six Bridgestone-shod cars start following the tyre controversy — Friesacher scored his only three championship points by finishing sixth from the six classified finishers.
His season was overshadowed by a sponsorship controversy. The primary backing had been brokered partly through the governor of Carinthia, Jörg Haider, and involved an unsecured state loan of US$500,000 via Hypo Alpe Adria. When his personal sponsors failed to pay the agreed sums, Minardi dropped Friesacher after the British Grand Prix, replacing him with Robert Doornbos. Years later, during a 2013 criminal trial, it emerged that the Hypo transfer had been made from an account in Friesacher's name without his knowledge, and was allegedly connected to a bribe paid to Haider.
Friesacher competed in the A1 Grand Prix series for Team Austria in 2006 and also tested the next-generation A1 GP car at Magny-Cours in 2008, sustaining three crushed vertebrae when a suspension failure caused a crash. In early 2008 he co-drove a Ferrari F430 for Risi Competizione in the American Le Mans Series, though back-injury recovery curtailed his season.
He subsequently became an exhibition and demonstration driver for Red Bull Racing and an instructor at the Red Bull Ring. Between 2017 and 2018 he drove F1 Experiences two-seater cars, giving passengers high-speed laps at Grand Prix circuits.
Friesacher's tenure at Minardi was brief and clouded by financial controversy, but his Formula 3000 record speaks to genuine pace: two race wins, back-to-back fifth-place championship finishes in 2003 and 2004, and a maiden podium at Monaco. His status as Red Bull's first-ever junior signing places him at the very beginning of the programme that later produced a generation of Formula One champions.