Decker grew up in a racing family with deep motorsport roots. Her father Chuck Decker once owned Eagle River Derby Track, host of the World Championship Snowmobile Derby, and won the 1987 World Championship Derby race there. The broader Decker family was prominent in snowmobile racing during the 1970s and 1980s, and the family's racing social circle overlapped with the family of Danica Patrick — Natalie's aunt Sue Decker introduced Patrick's parents to each other.
Decker herself won four karting championships in two years. She began racing 4-cylinder modified stock cars at age 12, moved to the Super Stock class in 2011, and won the 2012 class championship at Marshfield Motor Speedway. In 2014, she won seven limited late model features and two super late model features. Named to the NASCAR Drive for Diversity program in 2015 through Rev Racing, she also competed in the Alan Kulwicki Driver Development program in 2016.
She is the cousin of sisters Paige and Claire Decker, who also competed in NASCAR.
Decker made her ARCA debut in 2017 at Toledo Speedway for Venturini Motorsports, finishing eleventh after running much of the race inside the top ten. Venturini signed her for the full 2018 ARCA schedule, and she started the season by winning the pole at the Daytona season opener and finishing fifth in a crash-filled race. A hernia injury mid-season forced her to hand the car to Brennan Poole to finish a race. She ended 2018 seventh in points among drivers who competed in every race.
Her Truck Series debut at Daytona in 2019 under DGR-Crosley ended early when a left-front tire failure set the truck on fire on the first lap. An on-track incident at Kentucky Speedway later in the season with Spencer Boyd led to a confrontation in the garage, resulting in a verbal warning from a NASCAR official. She also tested an LMP3 sports car at Sebring International Raceway in January 2018 and raced in the Trans-Am Series for Tony Ave, winning the SGT ProAm Challenge Title in 2021.
The defining moment of Decker's career came on February 14, 2020, at the Daytona truck race. Driving for Niece Motorsports, she finished fifth, breaking Jennifer Cobb's nine-year record for the highest finish by a female driver in Truck Series history. The season also brought medical challenges: she missed Pocono after hospitalization for bile-duct complications following gallbladder surgery, and was unable to race at Las Vegas after a high heart rate and high blood pressure episode left her car parked on the grid, earning a last-place credit.
Decker transitioned to the Xfinity Series in 2021, driving the No. 23 for RSS Racing and Reaume Brothers Racing in at least five races beginning at the Daytona Road Course. She made additional Xfinity starts in subsequent seasons for various teams including DGM Racing and Emerling-Gase Motorsports, while also returning to the ARCA Menards Series. Health and sponsorship approval difficulties occasionally disrupted planned entries, including a sponsor rejection at Talladega in 2022 that forced a late withdrawal.
Decker was diagnosed with rheumatoid arthritis at age two, a condition she publicly disclosed in September 2019. She got engaged to fellow NASCAR driver Derek Lemke in December 2022 and married him on New Year's Eve 2023. In February 2025, she gave birth to their first child, a son named Levi, after experiencing delivery complications. Approximately six months later she returned to competition in the NASCAR Xfinity Series at Daytona International Speedway.
Natalie Decker's fifth-place finish at Daytona in February 2020 stands as a milestone for female competitors in NASCAR's Truck Series, bettering a record that had held for nearly a decade. Her career has been marked by a willingness to compete across diverse disciplines — ARCA, trucks, Xfinity, Trans-Am, and sports cars — and by continuing to race through significant personal health setbacks. Her family's multi-generational motorsport background, spanning snowmobiles and stock cars, adds a broader context to her place in American racing.