The 27-year-old Scot was offered new terms back in May but having refused to sign throughout the summer, he then failed to report back for pre-season training last Thursday, prompting Brentford manager Wally Downes' to act.
Fullarton joined the Bees on the eve of last season from Scottish Premier Division club, Dundee United and made a total of 27 league appearances, five as substitute, scoring once, on his debut at Huddersfield Town, during his one season at Griffin Park.
With pre-season now underway, that just leaves the futures of Stephen Hunt and Scott Marshall undecided, from the 'magnificent seven' who were offered new deals at the end of last season.