Allen made his NASCAR Craftsman Truck Series debut in 2005 in the Kroger 200 at Martinsville Speedway driving for Morgan-Dollar Motorsports, starting 21st and finishing sixth. He made one more start in 2005 for SS-Green Light Racing before signing with ThorSport Racing to run the final race of 2006 and ultimately replace Kerry Earnhardt in the No. 13 truck for the 2007 season. Allen ran his first full season in NASCAR in 2007 and at the Mountain Dew 250 at Talladega Superspeedway, matched his career-best finish with a sixth-place run. However, it was his lone top 10 on the season, and he was replaced by Shelby Howard for the 2008 season. For 2008, Allen returned to Morgan-Dollar Motorsports to drive the No. 46 Chevrolet Silverado to a 19th-place finish in the MemphisTravel.com 200 at Memphis Motorsports Park. He then drove two of the next three races in the No. 81 for the newly renamed Randy Moss Motorsports, after Randy Moss had bought a 50 percent share in Morgan-Dollar Motorsports. His first race was on July 19 at Kentucky Speedway with sponsorship from Rascal Flatts, where he finished 15th. Two races later, Allen made his third start of the year at Nashville Superspeedway with sponsorship from Rascal Flatts and GoDaddy, but crashed late in the race and finished 27th. Afterwards, Allen parted ways with RMM. After not racing in 2009, Allen returned to the series in 2010 for Team Gill Racing to run the No. 46 in the Nashville 200, starting 36th and finishing 29th. Allen has not raced in the series since.
Allen made his Nationwide debut in 2006 for FitzBradshaw Racing, racing at Memphis Motorsports Park and Phoenix International Raceway, with a best finish of 28th. In 2008, Allen ran two races with Sadler-Hamilton Racing, with a best finish of 29th at Daytona. The next year, Allen ran five races for Whitney Motorsports, but failed to finish all five. He also failed to qualify for a sixth race. He then signed to drive the No. 05 31-W Insulation/CertainTeed/Cash America car for Day Motorsports in 2010, running 18 races with a best finish of 11th. Allen also failed to qualify for four additional races. Allen ran two more races for Day Motorsports in 2011 before departing the team and the series. After several years out of NASCAR, Allen returned to compete in the Nationwide Series in 2014, driving for the debuting Martins Motorsports.
