In June 2008, Biffle signed a 3-year contract extension with Roush Fenway Racing. Despite going winless during the 26-race regular season, Biffle made for the Chase for the Sprint Cup that year and won the first two Chase races, at New Hampshire and Dover. In doing so, he became the first driver to win the first two Chase races in a season.

Biffle qualified for the Chase for the second year in a row in 2009. During a January 2009 test, Biffle managed to reach 218 miles per hour in a test for Roush Fenway Racing as part of evading NASCAR's testing ban. This became the fastest time ever achieved on this track by any competitor (amateur or professional).

In 2010 Biffle qualified for the third year in a row for the Chase. He scored 2 wins at Pocono and Kansas. For 2011, Biffle's season improved, thanks in part to the implementation of Ford's new FR9 engine. Biffle missed the chase in 2011 for the first time since 2007.

Biffle's first win of the 2012 season came at Texas Motor Speedway in the Samsung Mobile 500.