Webb was drawn to the sport of golf at a very young age. Her parents and maternal grandparents were golfers, and by age four Webb, with her toy club, was following them on the links around their hometown of Ayr, Australia. "They were about the only two people in the world who were patient enough to go out with a four-year-old and play golf on a Sunday morning," Webb later said of her grandparents.
Webb's parents bought her a real set of golf clubs for her eighth birthday, and soon after she started taking golf lessons from her neighbor, Kelvin Haller, a self-taught local golf player and greenkeeper at the Ayr course. Haller
lived next door to a drive-in movie theater, and during the day he would have his students practice their drives by hitting balls into the theater's empty parking lot. By the age of 12 Webb had decided that she wanted to be a professional golfer, and by her mid-teens she was well on her way, competing in amateur events and becoming one of the best golfers in the area. She and Haller's nephews, Ryan and Todd Haller, often played together, and Karrie and Todd eventually became engaged. He served as her caddie early in her career, but the two broke up in 1996.
Kelvin Haller has remained Webb's only coach since those first lessons, even though he suffered a stroke in 1990, at the age of 36, that left him almost completely paralyzed. He still helps Webb to improve her swing when she returns to Ayr during the off-season, and Webb says that having his coaching fresh in her mind is why she usually performs so well in the early events of the tour each year. The two have also developed a unique long-distance coaching relationship that they use during the season: Webb's caddie uses specialized, fixed cameras to record digital videos of Webb's swing from the same two angles each time, and then e-mails the videos, along with such data as the distance and location of each shot, to Haller. Haller then analyzes Webb's swing and gives her advice over the phone.