[6] Suffering from scoliosis, which was diagnosed at age 11 and treated by a spinal fusion when she was in high school, she missed her first collegiate golf season recovering from the surgery.

In her 2007 season, though a back injury kept Lewis out of the SEC Tournament, she won the NCAA Division I Championship and was selected Golf Digest Amateur of the Year.

[9] Following the college season, she won the 92nd Women's Southern Amateur and finished second in individual play in leading the U.S. team to a victory at the Copa de las Americas.

[8] Lewis qualified for the 2007 U.S. Women's Open in North Carolina, shot 78-73 in the tournament and missed the cut by three strokes to finish tied for 93rd.

[13] Following the Curtis Cup victory, Lewis turned professional, prior to competing in sectional qualifying for the U.S. Women's Open.

[17][18] Lewis's first official professional victory came at the 2011 Kraft Nabisco Championship, a major, where she led the field for the first two rounds, and then held off current world number 1 and defending champion Yani Tseng to win by three strokes.

Lewis won her second major title at Women's British Open in August at St Andrews with a score of 280 (−8), two strokes ahead of runners-up Na Yeon Choi and Hee Young Park.

In 2014, Lewis won the North Texas LPGA Shootout on May 4 for her ninth official victory on tour, six strokes ahead of runner-up Meena Lee.

[4] A week after a runner-up finish at the U.S. Women's Open at Pinehurst, Lewis won the Walmart NW Arkansas Championship on June 29.

[24] Lewis was the top female earner on the 2015 Golf Digest 50 All-Encompassing Money List, ranking at number 41.

[26] In 2020, Lewis won her first title in almost three years with a playoff victory in the Aberdeen Standard Investments Ladies Scottish Open at The Renaissance Club in East Lothian, Scotland.

[28] Lewis is married to Gerrod Chadwell, who has been the head coach of the Texas A&M Aggies women's golf team since 2021.