The Londoner becomes the fourth British title holder boxing under the Hatton banner joining Martin Murray (middleweight), Anthony Crolla (lightweight) and Gary Buckland (super-featherweight).
Theophane has mixed at the highest level and boasts an impressive record of 30 wins, 4 losses and one draw.
Hatton Promotions head Ricky Hatton is excited to have signed talented Theophane having once ruled the light-welterweight division globally.
Ricky said: “Ashley has a British title, but he has already proven himself as a world class boxer.
“He isn’t afraid of fighting away from home and proved that by beating DeMarcus Corley and Devlin Rodriguez in the United States.
“It only seems like last night that I was a world champion at light-welterweight, but here I am now promoting Britain’s next potential 140lb world title holder.
“Domestically there is nobody who comes close to Ashley and I hope he will be one of many Hatton Promotions boxers winning world titles in the next 12-18 months.”
Theophane, 31, is due to make the second defence of his domestic crown against Nigel Wright later this year.
He turned professional in June 2003 and captured the British title at Wembley Arena in February by outpointing Lenny Daws.
Theophane returned to the same venue in July and made a successful defence stopping Welshman Jason Cook in ten one-side rounds.