The Glasgow club lifted their first title since 2011 without kicking a ball as city rivals Celtic drew 0-0 with Dundee United at Tannadice on Sunday.
Within an hour of the result, hundreds of Rangers fans descended on George Square with scores of others seen outside Ibrox Stadium.
Online posts revealed that some supporters were hiring taxis from as far afield as Edinburgh to join the revellers.
Glasgow police re-issued a plea warning fans that they should stay away from the gatherings.
First Minister Nicola Sturgeon congratulated the club on their league success, but condemned supporters for coming together in large numbers and said their actions could “delay exit from lockdown for everyone else”.
Social media was awash on Sunday afternoon with polarising commentary focusing on the illegal gatherings.
While a majority appeared to share Ms Sturgeon’s view, a mix of opinions have been aired, with some voices adamant the fans should be allowed to toast their historic win in public.
Rangers fan @diane8315 tweeted: “I don’t agree with them all gathering however where I am there are people breaking lockdown rules 24/7 especially since-schools went back people are just back to normal so this doesn’t surprise me.”
@jetman824 said: “Let rangers fans celebrate. We waited 10 years for this.”
@Norther98293017 said: “Great to see people having fun again. More and more I see people who've had enough of Sturgeons politically motivated lockdown. Scotland has supposedly "dunbetta" than England on Covid, but we have a lockdown that is going to last month's longer.”
@JoshLally4 said: “Let them celebrate been locked away from the club they adore and just seen them win the league in 10 years.”
@Austchloe fumed: “I’m furious about this. I’ve not seen family for a year and these guys will delay any steps towards a new normal.”
@EilidhConvery tweeted: “Get them fined. They are the ones stopping me from seeing my gran and grandad. I haven’t seen them in over a year. This is beyond a joke now.”
@sallynicol001 added: “It is not acceptable for football fans to mess it up for everyone. Just for once celebrate at home and don’t screw it up for everyone else.”
@s83coffelt said: “This is a slap in the face to all the sacrifices made by so many over the past year. I couldn’t care less about football but I don’t want to be living in a lockdown for longer because people can’t celebrate at home.”
Justice Minister Humza Yousaf also took to Twitter to post: “Congratulations to @RangersFC - churlish not to recognise how well they have played this season
“I understand Rangers fans will be desperate to celebrate but please remember you must stay at home. No mass gatherings are allowed. We cannot risk any further spread of the virus.”
On Saturday scores of fans drew criticism for amassing at the ground in a similar fashion after Rangers set up their league victory with a 3-0 win over St Mirren.