Raised in Spydeberg, Norway, Solberg grew up around motorsport; both his parents were bilcross competitors and rallycross enthusiasts. He won a nationwide RC car championship in 1987 at age thirteen, and began bilcross competition in 1992 on the day after receiving his driving licence. He became Norwegian champion in rallycross and hillclimb in both 1995 and 1996, winning 19 of 21 events in the first of those years.
His younger brother Henning Solberg also became a rally driver, winning the Norwegian Rally Championship five times in a row from 1999 to 2003. Petter himself claimed the Norwegian Rally Championship in 1998, which brought him to the attention of international team managers.
Aided by compatriot John Haugland, Solberg secured a junior drive with Ford for the 1999 season. He made an immediate impression by finishing fifth at the gruelling Safari Rally after being promoted to nominated points-scorer when Thomas Rådström was injured, scoring points for both drivers and manufacturers championships.
In 2000, Solberg moved to the Subaru World Rally Team, then led by Richard Burns and Juha Kankkunen. His first WRC podium came at the Acropolis Rally in 2001, where he also notably surrendered positions to assist teammate Burns in his ultimately successful title challenge. In 2002, with Tommi Mäkinen as his new teammate, Solberg claimed his first WRC victory at Wales Rally GB after Marcus Grönholm suffered a crash.
Solberg entered the final round of the 2003 season, Wales Rally GB, with three drivers — himself, Sébastien Loeb and Richard Burns — in title contention. Burns withdrew before the event due to health reasons. Solberg then won the rally ahead of Loeb, securing his first and only WRC drivers' championship. He became the first Norwegian world rally champion.
His title defence in 2004 was undermined by retirements in mid-season despite winning five rallies, as Loeb proved increasingly dominant. Solberg finished runner-up in 2004 and again in 2005, the latter season also including a hat-trick of Wales Rally GB victories. His final WRC victory came in Australia in 2005, though a kangaroo strike on the last stage of that event actually retired him — his Wales win proving to be his last WRC victory. He continued with Subaru through 2008, contending for podiums but unable to recapture his championship form against Loeb's dominance.
When Subaru withdrew from the WRC at the end of 2008, Solberg established the Petter Solberg World Rally Team. Running a Citroën Xsara WRC in 2009, he became the first true privateer since Malcolm Wilson in 1993 to stand on the WRC podium, taking third in Cyprus and Sardinia. He upgraded to a Citroën C4 WRC for 2010, scoring podiums in Mexico, Jordan, Turkey and Bulgaria, and secured a top-three championship finish that year.
In 2011 his driving licence was briefly suspended in Sweden after a speeding offence. For 2012, Solberg returned to the Ford factory team, collecting multiple podiums. He confirmed at the end of 2012 that he would not contest the 2013 WRC season. His co-driving partnership with Phil Mills, which lasted eleven years and 152 consecutive events from 1999 to 2010, produced thirteen WRC victories and the 2003 world title before Mills stepped away from competition.
Solberg switched to the FIA European Rallycross Championship in 2013, finishing eighth in the Supercars category. In 2014 he won the inaugural FIA World Rallycross Championship, becoming the first driver to hold FIA World titles in two different motorsport disciplines. He successfully defended the crown in 2015.
In 2017, Solberg partnered with Volkswagen Motorsport to form PSRX Volkswagen Sweden, driving the Polo GTi RX. The team became dominant in World RX, winning 19 of 24 events across 2017 and 2018. His final World RX victory came at Lydden Hill in 2017. The team won the Teams' Championship in both 2017 and 2018, while Johan Kristoffersson claimed the drivers' titles. Solberg also made a brief WRC comeback at Rally Catalunya in 2018, finishing third in the WRC2 category.
Solberg retired from full-time motorsport after 2018, conducting a farewell tour in 2019 that included wins at Gymkhana Grid in Warsaw and a class victory at the Wales Rally GB. His son Oliver Solberg has since reached the World Rally Championship, and the pair won the Nations Cup for Team Norway at the 2022 Race of Champions. Post-retirement, Solberg was diagnosed with ADHD. He lives in Mitandersfors, Sweden with his family, including his wife Pernilla, daughter of 1980 European Rallycross Champion Per-Inge Walfridsson.