Midway through the 2007 season, Byrnes was rewarded with a three-year, $30 million contract extension with the Arizona Diamondbacks. Byrnes is one of a few players to have 50 stolen bases and hit 20 home runs in one season, having accomplished the feat in 2007. At the end on the 2007 season, Byrnes batted .286 with 30 doubles, 8 triples, 21 home runs, 83 RBI, and 50 stolen bases in 160 games. He led the Diamondbacks in doubles, RBI, stolen bases, caught stealing (7), and total bases (288). Byrnes was also 11 in National League Most Valuable Player Award voting, with 43 voting points. He was honored with a Fielding Bible Award as the best fielding left fielder in MLB.