The Brazilian midfielder joined the club from Hoffenheim in a then-club record deal in 2019 and has since amassed 179 appearances for the Magpies, scoring 25 goals.
Initially playing as a forward, the 27-year-old has been a revelation in a deeper box-to-box midfield role under head coach Eddie Howe and was a driving force last season as the club reached the Carabao Cup final and qualified for the UEFA Champions League.
In June 2023, Joelinton's club performances were rewarded with international recognition and he scored on his senior debut for Brazil in a 4-1 win against Guinea.
After agreeing a new deal with the Magpies, Joelinton said: "I feel great. I feel very happy and my family is happy. A lot of things have happened in my years here. I've learnt a lot and grown a lot, and for me to come here to Newcastle was the best decision of my career.
"I love playing for the club. I love the club, I love the fans. We had a lot of discussions and I always wanted to be here. I'm glad to continue and I hope to have success in the years to come."
Head coach Eddie Howe added: "This has been a big priority for us off the pitch and I'm absolutely delighted Joelinton has committed his future to the club.
"Joey is an exceptional player and person, and the love he has for the club is reciprocated by all of us here. He brings unique qualities to the group and undoubtedly makes us stronger.
"I'd like to thank everyone involved behind the scenes for bringing this to a swift and positive conclusion. We are all excited to see Joelinton in a Newcastle shirt for many years to come."