Saint-Maximin joined the Magpies from French Ligue 1 side Nice in an initial six-year deal before the start of the 2019/2020 season.
But the Frenchman has now agreed on an additional year and a huge pay rise after impressing in North East.
Speaking to NUTV, Newcastle's official channel moments after extending his deal, Saint-Maximin said: "I've played for a lot of clubs - Monaco, Nice, in Germany, but Newcastle, I feel like it's my home. The supporters give me a lot of love, the coach too, and my partners on the pitch.
“Everybody gives me love and when you have this, I feel it's my home and I hope this stays my home for a long time.
"Every club I'd been before, the fans loved me - but not like the Newcastle fans. That's really important, because for me, you have the football and everything, but you have the human and they give me something different. So if I can give back to the supporters and to the club with a new deal, I'm really happy."
Saint-Maximin was one of Steve Bruce’s best players in his first year in England as he was responsible for Newcastle’s forward propulsion due to his pace and energy.
He made 30 appearances in all competitions for the English side scoring four times and providing seven assists in the process.