The 26-year-old former Oxford man previously enjoyed two promotions with the Chairboys after signing from Crawley in February 2009, scoring 14 goals in 77 appearances.
Famous for a four-minute hat-trick against Chelsea during a pre-season friendly, Pittman makes his return to the club with the full backing of manager Gareth Ainsworth.
"He's a great character but more importantly he brings a lot to the team and he's still got his best years ahead of him," the 40-year-old boss told the club's official website.
"He gives us another attacking option. He's got pace, power and he's exciting to watch, plus he's a fans' favourite."