Prior to Jacksonville, Hackett was the offensive coordinator for the Buffalo Bills from 2013-14. In his second season with Buffalo, the offense finished with an 86.0 passer rating, the highest for the Bills since 2002. Buffalo also totaled 33 plays of 25-plus yards, No. 6 in the NFL in 2014 and the most for the Bills since 2000. In 2013, he led a Bills offense that ranked No. 1 in the NFL with a red-zone scoring mark of 95.5 percent and No. 2 in the NFL with an average of 144.2 rushing yards per game, the best rushing mark by Buffalo since 1992 (152.3 yards per game).

Hackett joined the Bills after three years at Syracuse, where he served as offensive coordinator and quarterbacks/tight ends coach in 2011-12 after spending the 2010 season as quarterbacks/passing game/tight ends coach. Under his direction, the Orange set numerous school records in 2012, including total offense (6,188 yards), yards per game (476.0), passing yards (3,757), touchdown passes (26), completions (295) and first downs (328). The Orange featured a 3,000-yard passer, 1,000-yard rusher and 1,000-yard receiver in 2012 for the first time in school history while eclipsing 500-plus yards of offense in seven games.