The England defender joined the Premier League club from Atletico Madrid in January 2022 and has played an integral role as Eddie Howe's side.
Newcastle qualified for the group stages of the Champions League in 2023 and 2025 and ended a seven-decade wait to win a major domestic trophy last season by lifting the EFL Cup.
"It's emotional and I'm really going to miss it," The 35-year-old Trippier said in joint statement released by the player and the club.
"I want to say a massive thank you to the supporters for all the support through the good and the bad times for me personally.
"You've always supported me, always stood by me. To my team-mates, it's going to be emotional. It's been an amazing journey with you guys.
"I'm going to miss you all, but to win a trophy with you guys was really, really special - the best of my career."
Howe paid special tribute to the right-back and said Trippier will be "giving absolutely everything to end his time here on a high".
"Kieran has been magnificent for us on and off the pitch," Howe added. "From the moment he walked through the door, he has helped to drive standards that have changed the club's trajectory.
"His performances on the pitch have been to the highest level. Building strong partnerships with the players around him. His outstanding technical ability helped elevate the team and his strong crossing ability helped create many goals and chances for his team-mates.
"His leadership skills have been invaluable. In difficult moments his experience has proved calming and his drive and will to win has inspired the players to keep pushing forward."