Watford announced the signing of the 22-year-old for an undisclosed fee on Friday – a deal which saw the full-back become the club's third summer arrival.
“I arrived here as a child, and I grew as a player and as a person with the dream of being able to defend these colours," Navarro wrote of his former club on twitter.
“After six seasons it is time to say goodbye to the club of my life, to face a new challenge in my career.
“I am leaving with the chance a new project and new objectives, but I will be thankful to this club and I will encourage you from a distance.
“I will always take you in my heart. Thank you for making me part of this wonderful minority."