By Sedara Philip
The 23-year-old Nigerian international only moved to Watford just over a year ago from Sparta Rotterdam for a fee believed to be in the region of €5m.
The 6ft 7ins keeper arrived at Watford with high hopes, having started his career in German football before becoming first choice at Sparta and also breaking into the Nigerian team.
He played 31 times for Sparta the season before moving to Vicarage Road, and had 16 caps for his country.
However, before last season started the then-head coach Rob Edwards announced that Daniel Bachmann was his first choice.
Okoye was on the bench regularly up until the World Cup break, but when the league season resumed in December he was only named in the matchday squad four more times with Ben Hamer becoming the back-up keeper.
Okoye then suffered a shoulder injury in April and was ruled out of action for the remainder of the season.
His only two appearances for the Hornets were in the home Carabao Cup defeat to MK Dons, and the away defeat at Reading in the FA Cup.
The path from Watford to Udinese is a well-trodden one: already this summer Hasane Kamara, Domingos Quina and Christian Kabasele have signed permanently for the Italian side, while defender Joao Ferreira has been sent there on loan.