I Ducali have been relegated to Serie B whereas The Hornets have earned promotion from The Championship and the 34-year-old will boost their midfield depth.
“The Slovakia international, 34, joins the Hornets with more than a decade of experience playing at a high level, having turned out for the likes of AC Milan, Genoa and Trabzonspor.
“A cultured midfielder, ‘Kuco’ has made 86 appearances for his national side, most recently appearing at this summer’s Euro 2020.
“He has played in both a holding midfield role and further up the pitch, scoring 13 times and notching five assists in the last two seasons for Parma.
“Welcome to Watford, Juraj!”
Kucka also left a farewell message on the Parma website.
“Today is a day in which I experience strong and conflicting emotions,” he said.
“I arrived in Parma and immediately felt at home. With the club, with my teammates, with the fans, with the Parmesan people.
“I have always given my all on the pitch, even in the most difficult moments, and I felt how everyone understood and appreciated it.
“I also wore the captain’s armband of a team that by tradition and history is second to few, in Italy and in Europe.
“The dream that I realised was that I felt appreciated as a man, rather than as a footballer.
“There is another dream that I have had since I was a child: to play in England, in the Premier League.
“This is why I decided to live out this new adventure. It was a difficult choice, particularly because of the affection I have for this ground and this club.
“I thank the club, who understand my decision, and who have always supported me over the years.
“My heart and the baggage that I carry with me will always be yellow and blue, and I will never forget everything we have lived through together.
“Thanks for everything, Parma, truly.