Whitt moved up to stock cars in 2010, the same year he won the Super License award for USAC. Whitt ran for the Camping World East Series championship, where he impressed by winning the pole in his first start at Greenville-Pickens Speedway. Whitt eventually finished fourth in points. Whitt was rewarded with making his Nationwide Series debut at Phoenix International Raceway, where he made the race and finished 15th.
The next week, Whitt ran both the Nationwide and Truck Series events at Homestead-Miami Speedway, finishing 17th and 28th respectively, running the Truck race for Turn One Racing.
Whitt drove for Turn One in 2011 and competed for Rookie of the Year honors. After failing to qualify in the No. 60 truck at Daytona, Whitt drove the No. 93 for RSS Racing before returning to Turn One. Whitt won the pole at Darlington, and became the first rookie to lead the Truck Series points after Charlotte, winding up ninth in points at the end of the season.
He also drove a third Red Bull Racing Team entry in the Sprint Cup Series in the final two races of the season at Phoenix International Raceway and Homestead-Miami Speedway, but ended Homestead with a DNF near the finish of the race.
With the closing of Red Bull's racing program after the 2011 season, Whitt signed a contract with JR Motorsports to drive that team's #88 Chevrolet in the Nationwide Series in 2012, competing for Rookie of the Year honors. He also competed on a start and park basis in the Sprint Cup Series in selected races for Turn One Racing and Circle Sport. At the October Talladega race, Whitt was running in the top 15 before a crash involving Carl Edwards and Joey Logano took out Whitt on lap 17.
In 2013, Whitt and JR Motorsports parted ways with the team citing lack of sponsorship. He later joined forces with Tri-Star Motorsports, driving their #44 Nationwide entry from Dover onward. He earned his first top-ten of the year with an eighth-place finish at Road America.
Late in the season, he ran seven Sprint Cup races with Swan Racing Company as a replacement for David Stremme. The team then hired him for the full 2014 season, placing him in their new second team, the #26.