Mullings, who started his career with Bristol Rovers, for whom he made a handful of first-team appearances, was in his second spell with the Tigers since re-joining from Weston-super-Mare in 2017.
The experienced 30-year-old has also worn the colours of Torquay United and Oxford City.
Chippenham manager Mark Collier told his club`s official Pitchero website: "Darren will bring experience and quality to the squad. In our recent game against Gloucester, Darren was the outstanding player, and the fact that he can cover several positions makes his arrival a very welcoming one.”
Mullings will be a part of the squad for Saturday's game against Hampton & Richmond Borough.