The 21-year-old scored one try in two appearances for the Welsh region but crossed eight times in 26 games for Welsh Premiership side Cardiff RFC, who come under the umbrella of the Blues.
Bath have also handed a new two-year contract extension to back row Levi Douglas, 20, who joined the English Premiership club's academy in December.
He has made three senior appearances since signing from French side Oyonnax.
On Tuesday, Bath announced Argentina wing Horacio Agulla will leave the club at the end of the season.
Mike Ford's side are ninth in the table ahead of their final match of the season against Leicester Tigers on Saturday,
Bath have signed Cardiff Blues' Welsh wing Harry Davies ahead of next season.