Duffy has penned a new four-year deal at the club. The 25-year-old centre-back joined the Seagulls from Blackburn last year and made 34 appearances in the Championship last campaign.
Meanwhile, Dunk and Knockaert have both put pen to paper on five-year contracts. Centre-back Dunk has been at the club since 2013, while winger Knockaert joined the team in January 2017.
Hughton said, according to Sky Sports: “It’s been a really straightforward process getting everything completed and I’m absolutely delighted that three key members of the squad have committed their futures to the Albion.”