Rangers are Scottish champions for the first time in 10 years after Celtic drew 0-0 with Dundee United.
Steven Gerrard’s side, who beat St Mirren 3-0 on Saturday, have a 20-point lead with six games remaining.
It is former Liverpool and England captain Gerrard’s first trophy as a manager in his third season at Ibrox, and ends Celtic’s bid for an unprecedented 10th successive crown.
It is the earliest Scottish title win in chronological terms.
Rangers have dropped just eight points in an unbeaten Scottish Premiership campaign so far, with their victory on Saturday their 28th win in 32 matches.
They have scored 77 goals and conceded just nine – only two of which have been at Ibrox.
The Glasgow club were in the bottom tier of Scottish football as recently as 2012 after their financial collapse, and returned to the top flight five years ago.
Rangers’ first game as champions will be the third Old Firm game of the campaign at Celtic Park on March 21.
‘They thoroughly deserve it’ – reaction
Former Rangers player and manager Graeme Souness on Sky Sports: “Delighted for Steven Gerrard and all his team. Celtic have had a period of dominance, which has been, I’ll say, uncomfortable for us Rangers supporters. They thoroughly deserve it. They’ve been fantastic all season and I just wish I was in Glasgow right now.”
Former Liverpool defender Jamie Carragher on Sky Sports: “They must have been terrified for years that record [nine straight titles] would have been beaten by Celtic. When Gerrard came in, that was the name of the game to stop Celtic achieving that. They’ve come a long way, but they’ll be hoping the glory days are back.”
Former Rangers captain Lee McCulloch on BBC Radio 5 live: “It’s been a little bit emotional; 10 years is a long time to wait. Every Rangers fan all around the world will be celebrating this tonight.
“The club hit rock bottom. It’s been a slow climb back up but today is all about Steven Gerrard and his squad. The changes Steven has made, the leadership he’s shown, the recruitment, on and off the pitch the club has been fantastic.”