The former Swindon loanee has agreed a three-year deal at the County Ground.
Ajose spent time on loan in Wiltshire from Peterborough United at the start of the 2013/14 season, netting ten goals in his first spell.
Since leaving the Posh, he has also been out on loan at Crewe Alexandra during his stint at Elland Road.
Watch Nicky’s first interview since re-joining the Town on STFC Player by clicking here.