The 26-year-old, who made his name with Stevenage Borough and Stockport County, only joined Leeds in January but was deemed surplus to requirements within a matter of months.
Alex first-team coach Steve Holland told the club's official website: "We are delighted to have finally signed Anthony.
"Our interest has been well-documented ever since he was made available in January. We missed out to Leeds then, but kept an eye on the situation.
"We tried again recently, but he wanted to try and force his way into the squad there.
"However, with Leeds bringing in and looking to bring in some new players, he has found that difficult and we were again alerted to his availability."