The Lisbon-born manager had a 15-year professional playing career in Portugal before retiring with second-tier Estoril at the age of 33 in June 2011.
Silva was appointed director of football at the Portuguese club shortly after retiring and then became Estoril's manager early in to the 2011/12 season.
Ater guiding them to the top flight as champions, Silva led Estoril to UEFA Europa League qualification in the following season.
One season at Sporting followed, which included silverware via the Taca de Portugal, before Silva led Olympiacos to the Superleague Greece title in 2015/16.
A small hiatus from football was ended on 5 January 2017, when Hull City announced the Portuguese as the club's new head coach.
An upturn in Hull's results followed for the team bottom at Christmas, including a long unbeaten run at home.
However, the club were relegated with one match to spare, with Hull announcing Silva had opted to leave his position at the KCOM Stadium on 25 May 2017.
Two days later, Watford announced Silva as Walter Mazzarri's replacement at Vicarage Road.
The 2017/18 campaign started well for Watford with the club temporarily moving into fourth after a 2-1 over Arsenal in mid-October.