Waddecar signed for Brig from local side Lostock St Gerard's and made his first team debut at Irongate in September 2010 in NPL Division 1 North against Cammell Laird.
In October 2019 he hit the milestone of 450 appearances for the club.
He will now make the move to FC United on a 12-month contract to feature under manager Neil Reynolds.
Reynolds said: "I am absolutely thrilled that we have been able to bring Ali to FC. He is a goalscorer of the highest quality who leaves everything on the pitch, our fans are going to love him. Roll on the new season."
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