Vata was wanted by Brendan Rodgers’ Scottish champions to stay in Scotland, but the 19-year-old has been enticed to continue his career south of the line.
The transfer is projected to bring in £237,000 for Celtic, who will receive a training compensation sum.
Watford is currently nearing the end of the contract, and the Italian publication Tutto Mercato claims they will officially announce Vata’s arrival on Friday.
He signed a five-year contract with the Hornets after passing their medical examinations. Watford had competition from Lazio and Palermo, two Italian teams eager to sign Vata after observing his development.
Vata will be leaving Celtic after just six senior games played for the team. Throughout the course of the upcoming season, the Irishman—this time with Watford—will be searching for additional chances to have an influence at the senior squad level.