Mason Diaz is a second generation, up-and-coming championship racer from Manassas, Virginia.
Diaz started racing as a kid, getting involved in the sport going to the track with his dad, Michael Diaz. Michael Diaz raced in Legends at Old Dominion Speedway before he purchased Southern National Motorsports Park. When Old Dominion closed in 2012, Mason Diaz began competing regularly in Legend Cars. In 2015, Diaz began competing part-time in Pro Late Models in the PASS Series before moving up in 2015.
In 2016, he continued to compete in Legend Cars, but also began racing regularly in Pro Late Models at Southern National Motorsports Park. Later in the season, Diaz competing in the ValleyStar Credit Union 300 at Martinsville Speedway. He also ran in the Allen Turner Hyundai Snowflake 100 at Five Flags in December 2015, gaining attention with his top-10 finish.
In 2017, Diaz won the NASCAR Whelen All American Series Division I track championship at Southern National Motorsports racing in a Late Model Stock Car prepared by Mike Darne Racing. Diaz won multiple races at Southern National and also scored a victory in the prestigious Rusty Harpe Memorial at Caraway Speedway. He also won NASCAR Whelen All-American Series Rookie of the Year honors in Florida and North Carolina. In addition to his success in late models, he made his first start in a NASCAR Camping World Truck Series, impressing with a top-15 performance before a cut tire derailed his strong performance.