Video footage posted on social media shows the fans holding a banner that read: “Today nothing else matters.”
A large number of police were on standby outside the ground, where fans let off flares as the team buses arrived.
Supporters were told not to leave their homes for the match by Nicola Sturgeon earlier this week, who said doing so would risk their health.
The First Minister’s call was backed by Celtic boss Neil Lennon and Rangers manager Steven Gerrard.
Yesterday Gerrard, 40, urged fans “to stay at home, stay safe, keep their families safe and do the right thing.”
Speaking on Thursday the First Minister also urged Sky Sports to screen the game for free in order to encourage people to remain at home and not gather in large groups to watch the hotly-anticipated clash on Saturday afternoon – the first meeting between Celtic and Rangers since December 29 last year.
Ms Sturgeon said: “Enabling people to watch the match in the comfort and safety of their own home and reduce the temptation people who don't have access to pay-to-view services might have to go and watch the match somewhere else.”
Labour MP Ian Murray, formerly the chairman of Hearts’ supporters group Foundation of Hearts, called on the First Minister to go further and postpone the Old Firm match altogether, citing the threat it posed to public health.