Clucas, 25, impressed as the Tigers completed a shock victory over champions Leicester on the opening day of the season and has now committed himself to 2019.
With the club seemingly close to a takeover by a Chinese group there has been no investment in the first-team squad this summer, but Clucas' new deal shows some signs of positive movement.
He arrived at the KCOM Stadium last July and was an important part of the team that won promotion via the play-offs.
Clucas said: "I'm delighted to extend my stay with the club
"I had a wonderful first season here, which culminated in the cl ub winning promotion to the Premier League
It was a thoroughly enjoyable campaign and one that will stay with me for a long, long time
"I've got a great connection with the staff, players and fans here
It's a fantastic group to be part of
The spirit in the squad is second-to-none and we are determined to achieve our goals in the Premier League this season."
Mike Phelan, currently acting as caretaker manager, added: "Sam was an important part of our success last season, with his creativity and ability to score goals from midfield
"However, it is not just his ability that makes him a key part of the squad, but also his commitment, determination and focus
I'm confident that he will continue to flourish in the top flight of English football after his impressive performance against Leicester on Saturday and be a central component of the squad, not only this season but in the years to come."
Hull had just 13 fit senior players to choose from against the Foxes, supplemented by five academy players on the bench
Source : PA
Source: PA