Williams joins Welsh boxing greats Howard Winstone, Joe Calzaghe and Enzo Maccarinelli in winning the award, which he will receive on 10 October.
Williams, 24, faces undefeated Ahmet Patterson in his next contest.
"I'm absolutely delighted to have been honoured with this award," said former Commonwealth champion Williams.
"To have my name on a trophy alongside so many great fighters such as Ricky Hatton and Joe Calzaghe makes me very proud."
British super welterweight champion Liam Williams has been named the young boxer of the year by the Boxing Writers' Club.