Sampey debuted in NHRA Pro Stock Motorcycle competition in 1996 and immediately demonstrated exceptional consistency. She qualified for every event she entered from her professional debut, building an active streak of 182 consecutive race qualifications before a lack of sponsorship forced her to sit out the 2009 season, breaking the run.
Her championship three-peat from 2000 to 2002 placed her among the elite of the sport. Over the course of her Pro Stock Motorcycle career she recorded 46 event victories, making her the second most successful woman in NHRA history behind Erica Enders, who surpassed her with a 47th win in 2023. Her win-per-round ratio across her career stands at 71.9 percent — 364 round wins from 506 competitive rounds.
On 23 June 2007 at Old Bridge Township Raceway Park in Englishtown, New Jersey, Sampey set the national Pro Stock Motorcycle elapsed time record with a 6.871-second run, taking her 42nd career pole position in the same event. At the time, she was five wins behind Dave Schultz's all-time Pro Stock Motorcycle wins record.
Her primary sponsors throughout the Suzuki years included R.J. Reynolds' Winston brand and the U.S. Army, campaigns that gave her national visibility beyond the sport.
Sampey announced her retirement from professional drag racing on 11 March 2010, following the loss of sponsorship that had caused her to miss the 2009 season. The retirement was not permanent. In September 2014, she announced a return to competition before the close of the 2014 NHRA season, with plans to contest the championship in 2015. She raced through the 2022 season before departing Vance and Hines Suzuki at the end of that year.
In August 2023, Sampey transitioned from Pro Stock Motorcycle to Top Alcohol Dragster, joining Antron Brown's AB Motorsports Accelerate programme. After earning her A/Fuel licence in Jasmine Salinas' Top Alcohol Dragster, she debuted at the Texas Motorplex as preparation for a full 2024 sportsman season, with a longer-term ambition of reaching Top Fuel. In her Top Alcohol Dragster debut she qualified 16th and last, then defeated Mike Coughlin in the first round and Tony Stewart in the second before losing to Kirk Wolf in the semifinals.
Sampey is one of very few women to have won a major motorsports championship title in any discipline. She, Erica Enders, and Shirley Muldowney are the only female drag racers to have won more than ten NHRA events, and the only three women in the sport to win more than one championship: Muldowney with three Top Fuel titles, Enders with five Pro Stock titles, and Sampey with three Pro Stock Motorcycle titles. She is considered the second most successful woman in professional motorsports history by race wins, behind Enders.
Her 45 all-time top-qualifier awards remain a class record in Pro Stock Motorcycle, and her 71.9 percent round-win ratio across over 500 competitive rounds reflects a level of execution rarely matched in the sport.