The cordoned zone in Glasgow Green was designed to welcome fans and families throughout the international football tournament, but around 74,000 of its seats went unfilled.
Organisers of the zone said the turnout was down to high numbers of “no shows” among people who had booked tickets for the free gatherings.
However, Scottish Labour’s Paul Sweeney said the poor attendances raised questions over the merits of the initiative.
The Glasgow MSP told The Scotsman: “The fact that there was evidently such a lack of interest in the fan zone does beg the question of why the Scottish Government were so willing to commit public funds and resources to setting it up.
"At a time when the city's hospitality sector was crying out for help and increased footfall, priority was given to big business and it's unforgivable.
“It's astounding that there was no requirement for testing before entry, something that's entirely at odds with other mass gatherings across the UK, and we know from Public Health Scotland that over 50 cases were tracked directly to the fan zone itself as a result.”
Mr Sweeney added: "The whole episode has been nothing more than a dangerous vanity project for the government.
“Once again, the interests of big business and multinational sponsors were put before local venues and the people of Glasgow were prevented from being able to use vast swathes of one of the most accessible parks in the city.”
The total cost to the public purse of the fan zone is in excess of £1 million, with £817,000 alone going to G4S for event security, crowd management and stewarding.
Colin Wilkinson, managing director of the Scottish Licensed Trade Association (SLTA), said the roll-out of the fan zone was a “slap in the face” to pubs and other licensed premises, which were and continue to operate under Covid-19 restrictions.
He said: “Our industry has spent millions of pounds making their premises as safe as possible during the pandemic, and I think these figures show that football fans prefer to watch games in the pub.
“But because we are still operating at reduced capacity, even if a pub is classed as full, it will still only have around a third of its normal customers. We still need financial support beyond level zero.”
The capacity for each of the 38 sessions at the Glasgow Green fan zone was up to 3,000 people as each ticket provided a table that could seat up to six.
A Uefa Euro 2020 Glasgow spokeswoman said all the tickets were booked shortly after they became available.
However, many ticket holders did not bring the maximum number of friends or family with them, meaning many tables were not used to full capacity, and some ticket holders did not turn up at all.
David McDonald, the chair of Glasgow Life and depute leader of Glasgow City Council, described the fan zone experience as “an unforgettable 31 days”.
He said: "The Uefa Euro 2020 Fan Zone at Glasgow Green has been a vibrant hub of activity. We've been able to showcase the best that Glasgow and Scotland have to offer."
The fan zone project was green-lit after talks involving health secretary Humza Yousaf and Glasgow City Council.
Coronavirus testing was not mandatory to gain entry, but some 17,000 lateral flow tests were posted to ticket holders, with a further 4,000 handed out on site.
Scottish Government statistics suggests that 55 people who tested positive for the virus told contact tracers they had visited the fan zone.
Figures show that, overall, the free-to-enter fan zone operated at one-third of its 114,000 seat capacity and it did not reach it’s 3,000-strong capacity on any of the 38 days it was open.
Attendance peaked on June 18 at 2,214 as Scots settled down to watch their team hold England to a 0-0 draw at Wembley.
Ultimately, defeats at Hampden Park to the Czech Republic and Croatia destroyed Scotland’s hopes of making it through to the knock-out stages of the Euros.
Alongside the live football, more than 10,000 people attended music and comedy gigs at the fan zone, including Glasgow Jazz Festival evenings and the Scottish drag show ‘Queens on the Green’.