Former Crawley Town boss has become the first Englishman to win the Indian Super League.
The 63-year-old led Chennaiyin FC to the title on Saturday.
The former Aston Villa, Derby and Queens Park Rangers boss joined the Reds in December 2013 after replacing Richie Barker before stepping down just over a year later due to health problems.
In a 28-year managerial career, John Gregory's trophy cabinet has been rather empty, bar the 2001 Intertoto Cup.
Gregory's Chennaiyin side beat Bengaluru FC 3-2 in the final and he celebrated by extending his contract with the club on Monday.
He told the BBC: "If I'm still the only Englishman to have won it in 20 years' time I'll be happy.
He added: "It is enormously satisfying.
"I've never been to India before and trying to acclimatise ourselves to the way people live, the way people drive, the way people treat you with respect.
"From a professional point of view, there's a lot of red tape that we have to adhere to here. Obviously, some of that is frustrating, but you have to get used to it. The travelling is also different and a bit long."