As part of EGR's development program, Larson competed for Revolution Racing in the NASCAR-sanctioned K&N Pro Series East, a regional touring and feeder series, for the 2012 season; he scored a top ten finish in his first race in the series, won the pole for the fifth race of the year, and in the sixth race of the fourteen-race season went to victory lane at Gresham Motorsports Park in Jefferson, Georgia, leading the final five laps of the race to score his first NASCAR win.
He also made his debut in the ARCA Racing Series at Michigan International Speedway, driving for Eddie Sharp Racing; he finished 13th in the event.
Larson returned to ARCA in 2014, winning at Pocono from the pole.
In late June 2012, Larson made his debut in NASCAR's national touring series, driving the No. 4 for Turner Motorsports in the Camping World Truck Series event at Kentucky Speedway; he finished in the top ten in his first race in the series.
Everett F. Larson was launched on 28 January 1945 by Bath Iron Works, Bath, Maine; sponsored by Mrs. H. Larson, mother of PFC Larson; and commissioned on 6 April 1945, Commander H. Meyers in command. She was reclassified DDR-830 on 18 March 1949.
In his first season in a NASCAR touring series, Larson won the 2012 K&N Pro Series East championship, with two wins and twelve top tens in 14 races, overcoming the five wins of Corey LaJoie (son of two-time Busch Series champion Randy). Larson was also named the series Rookie of the Year.
For 2013, Larson moved full-time to the NASCAR Nationwide Series, driving the No. 32 for Turner Scott Motorsports. On the last lap of the DRIVE4COPD 300 at Daytona International Speedway, he was involved in a violent crash, in which his car went airborne and pierced the catchfence, completely ripping the front end of his car off. He was unharmed, but the debris hurt a number of spectators in the stands.
To dissuade the two-car tandem and return to pack racing, a new superspeedway package was introduced for the 2012 season, including a curved spoiler and a lower and longer rear bumper. The tandem remained prevalent in the Nationwide Series until 2014, when pushing was banned after a massive crash at the end of the 2013 DRIVE4COPD 300, in which 28 spectators were injured by flying debris off of Kyle Larson's airborne car.