It is understood that the 28-year-old midfielder will undergo a medical with the Hornets on Thursday before finalising a £4.1million transfer to Vicarage Road.
Sky Sports indicates that Suarez will sign a three-and-a-half-year deal with Quique Sanchez Flores' side.
The three-time Spain international, who joined Fiorentina from Atletico Madrid in the summer, played 35 times under Flores during their time spent together at Vicente Calderon and will provide competition for Ben Watson and Etienne Capoue for a central midfield position.
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!