[1] She retired on 15 September 2019 after holing the winning putt for the European team at the 2019 Solheim Cup, notwithstanding that she had been away from golf for almost 20 months on maternity leave prior to the event.

[2][5] She represented Norway in the world amateur team championship for women, the Espirito Santo Trophy in 1998 and 2000, finishing as the leading individual in her second appearance.

[8] Pettersen turned professional in September 2000 at age 19 and gained her Ladies European Tour card with an 11th-place finish at the 2001 LET Qualifying School.

[10] Pettersen started 2002 with a playoff loss to Karrie Webb in the AAMI Australian Women's Open, and two more top ten finishes led to her winning a place on the European team for the 2002 Solheim Cup.

[10][23] Pettersen became the first Norwegian LPGA winner at the 2007 Michelob ULTRA Open at Kingsmill, beating Jee Young Lee in a playoff.

[25] In October at the Longs Drugs Challenge, Pettersen won her third LPGA victory, beating Lorena Ochoa in a playoff and then claimed wins number four and five in Korea and Thailand.

[26][27] On 31 December 2007, she reached the number two position in the Women's World Golf Rankings, surpassing Karrie Webb and Annika Sörenstam, trailing only Lorena Ochoa.

[29] In September 2009, Pettersen won her sixth LPGA Tour event and first in two years at the CN Canadian Women's Open at Priddis Greens Golf & Country Club in Calgary, Alberta.

Pettersen won the event by five strokes over Karrie Webb, Momoko Ueda, Morgan Pressel, Ai Miyazato and Angela Stanford.

Pettersen broke her 20-month victory drought in May when she captured the Sybase Match Play Championship at Hamilton Farm Golf Club in New Jersey.

Playing in cool, rainy conditions, she won all six of her 18-hole matches over four days, and defeated, among others, then-world number one Yani Tseng in the quarter-finals, and Cristie Kerr in the finals.

Pettersen won on the first extra hole with a par after Choi put her approach shot in the water to double bogey.

The European team captain Carin Koch and vice captain Annika Sörenstam tried to convince Pettersen to change her mind and concede the putt, but as it was a fact that Lee had picked up her ball without the putt being given to her, it wasn't a possibility within the rules of golf, for the players to agree on the outcome of the hole and change the sequence of events afterwards.

For the 2017 the Solheim Cup match, 18–20 August in West Des Moines, Iowa, United States, Pettersen qualified for the team by her Women's World Golf Rankings, and should have made her 9th consecutive appearance, but withdrew with a back injury.

[30] Pettersen was picked for the 2019 Solheim Cup European team by captain Catriona Matthew, who was criticized for choosing a player who had been away from golf for nearly two years on maternity leave.

That pick proved to be astute, as, on 15 September 2019, Pettersen holed her birdie putt on the 18th in her singles match at Gleneagles PGA Centenary Course to defeat Marina Alex, 1 up, to win the Solheim Cup for Europe.