"I had a lot of good memories from playing here," said Mason, who left East End Park after six years in 2007.
"It was a tough decision at the time to leave here, but things happen like that in football."
Mason could make his second Pars debut in Sunday's Scottish Cup fifth-round tie at home to Celtic.
"There are a lot of games left this season, so I'll try and prove myself and hopefully I can prove my worth and get a longer contract," Mason told Dunfermline's website.
Mason joined Dunfermline from Manchester City and left for St Mirren after their relegation to Division One.
He moved to Hamilton at the start of the season but only made five appearances before being released.
Source: BBC Sport
Source: BBC Sport