It emerged in Monaco that the famous British team is offering the 2008 world champion a more than $150 million, new five-year contract, that would extend his McLaren tenure beyond a decade and his 33rd birthday.
It would also make Hamilton, 27, F1's highest paid driver.
"Without McLaren," said triple world champion Stewart, "Lewis Hamilton would not exist, certainly in terms of where he is in his career.
"And McLaren are one of the great teams in Formula One -- not in the past, but now," the famous Scot told the Daily Mail.
"They employ great engineers. They invest in winning."
"Even if they could build a winning car, he would have Fernando Alonso as his teammate -- and he's been there," added Stewart.