“It's like home, especially with the fans, the players, the staff,” Son said.
"There was no decision. It was easy. I'm so happy to be here and will be so glad to see the fans again soon.”
No financial details were given.
Tottenham tweeted: “ He's here to stay.”
“Everyone can see the real positive impact he has on the club, both on and off the field, and we are delighted that he will play a part in what we are trying to achieve in the coming years," football managing director Fabio Paratici said.
With Son's future seemingly set, new manager Nuno Espirito Santo can now turn his attention to Kane. Last week, Nuno affirmed that he expects Kane to return.
After Tottenham's seventh-place finish in the Premier League left it out of the Champions League, Kane indicated he wants out. The England and Tottenham captain was frustrated with the direction of the team and lack of trophies.
Son told club media that he's ready to shoulder the responsibility of winning trophies.
“I want to win something with Tottenham,” he said.
“This is my aim and this is also the fans' aim. This is a massive massive club — big opportunity. I want to be part of this, I want to take a big responsibility of this. That's what I signed for.”