Sean O’Hair turned professional right after finishing his junior year in high school. His father helped him with this decision selling their business in Lubbock to help with his golf training and promptly enrolled him at the David Leadbetter Golf Academy.
He played in the Nationwide Tour in 2001 as well as the Gateway Tour and the Cleveland Golf Pro Tour. By 2004, he finished T28 at the First Tee Arkansas Classic of the Nationwide Tour. His performance earned him a Tour card for the 2005 season.
2005 was a great year for O’Hair who won his first victory in the John Deere Classic at the age of 22. He earned a record-high $720,000 prize money, a slot on the British Open and climbed to the World No. 53 spot (from No. 93). The following week, at the British Open, he finished with a T15 scoring average.
In 2006, he participated in 30 events, finishing T12 at the PGA Championship and T14 at the British Open. He also earned the third spot at the Canadian Open. By the next year, O’Hair was on a roll, earning almost $2 million in prize money.
He started the year with a T7 finish at the Verizon Heritage. He also performed well at the PLAYERS Championship, pitted against Mickelson in his group. He finished T11 at the end of the championship. At the Deutsche Bank Championship, he finished with a T9 scoring average. He also scored a season-high with a T4 spot in the Fry’s Electronics Open.