Stenhouse began racing in ARCA in 2008 for Roush Fenway Racing. On May 10, 2008, in only his sixth race in a stock car, Stenhouse, Jr. won his first ARCA RE/MAX Series event at the Drive Smart! Buckle Up Kentucky 150 at Kentucky Speedway in Sparta, KY. He had two wins in 21 races and finished fourth in the season ranking as a rookie.
For 2009, he began competing in partial schedule in the Nationwide Series at events that conflicted with the Sprint Cup schedule. He had his first Top 10 finish at Kentucky Speedway when he finished ninth. At the following race in Milwaukee, he led 46 laps in the later stages of the race and finished fifth.