Large groups of people have congregated in George Square in Glasgow as well as outside Ibrox stadium.
Cameras at both locations showed large groups setting off fireworks and flares, many without facial protection or adhering to social distancing rules.
Police said they have made ‘a small number of arrests’ across the city.
One local MSP described the scenes as disgraceful and demanded answers from Police Scotland Chief Constable Iain Livingstone.
Meanwhile First Minister Nicola Sturgeon tweeted: “I congratulate Rangers FC on the title win and recognise what a moment this is for fans.
“But gathering in crowds just now risks lives, and could delay exit from lockdown for everyone else.
“If those gathering care at all about the safety of others and the country, they will go home.”
The First Minister later urged Rangers club bosses to intervene to appeal to fans to clear the streets.
She wrote: “I share folks’ anger at this. Everyone has made so many sacrifices in the past year & seeing a minority risk our progress is infuriating & disgraceful. It is deeply unfair to the entire country, and the police have a hard enough job already. Please ask fans to go home @RangersFC.”
Rangers won their first title in ten years without kicking a ball as rivals Celtic failed to beat Dundee United at Tannadice with a 0-0 result.
Several jubilant fans took to social media to say they were on route to Ibrox to celebrate spoiling Celtic’s quest for an unprecedented ten league victories in a row.
Within minutes of the final whistle hundreds had arrived at the ground, many appearing to ignore rules on facial coverings and social distancing and letting of flares as they revelled in the result.
Some fans said they were hiring taxis from as far afield as Edinburgh to join the party.
After several hours celebrations at Ibrox a large group of fans was escorted by police away from the ground.
A procession later arrived to join up with revellers at George Square.
Glasgow Kelvin Msp Sandra White took to Twitter to demand answers from Police Scotlamd Chief Constable Iain Liviongstone on the apparent ‘softly softly’ approach adopted by his officers.
She wrote: “ As MSP GCC [Glasgow City Centre] can I ask what Police Scotland are doing about the disgraceful situation my constituents are having to endure we have people blatantly breaking the law, drinking in the street and general anti-social behaviour I would like a reply.”
In a Facebook post Chief Superintendent Mark Sutherland, Divisional Commander for Greater Glasgow Division, said: “We are continuing to police the ongoing gatherings of football supporters in both George Square and outside Ibrox stadium today.
“Public safety remains our utmost priority and I would again remind fans that, in line with the current Scottish Government Coronavirus guidelines, all gatherings are currently restricted.
“Officers have made a small number of arrests and issued fixed penalty notices for breaches of the coronavirus restrictions, minor incidents of disorder and the use of pyrotechnic devices.
“We will continue with an appropriate policing response, as officers engage with those present, explain and encourage them to comply with the restrictions. Where appropriate, we have moved to enforcement and will continue to do so.
“Our response will be measured and appropriate. We understand fans want to celebrate but they must do so safely and lawfully. We continue to ask everyone to do the right thing to stop the spread of the virus.”
Fans were seen at Queen Street station alighting from trains, with one witness saying that large numbers were not wearing masks.
Justice Minister Humza Yousaf 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.”
Celtic played Dundee United at Tannadice Park on Sunday, and 55 minutes into the match, a flare was thrown onto the pitch, presumed to be a reference to the fact today’s victory marks a 55th title for the Ibrox club.
Rangers fans also taunted their rivals by hiring a plane to fly over United’s stadium with a banner which read ‘Can you see us now? #55 titles.’
Yesterday (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.