The former Welsh Under 21 cap was released by 'Pool boss Neale Cooper last month after making just one league appearance last season.
With Aidan Davison departing from Blundell Park today, Russell Slade moved quick to bring in a potential replacement and the 26-year-old will be hoping he can fill that void.
Despite his age, Williams has a whopping nine clubs under his belt - most on loan deals though.
The bulk of Williams first team football last season came on loan at Stockport, ironically his last game for the Hatters was the 2-1 win over Town at Edgely Park in April, Graham Hockless scoring a second half wonder goal for the Mariners past Williams.