From the start of the football tournament on June 8 until the final last Sunday, just 40,000 people visited the outdoor area in Glasgow Green to watch matches.
Figures show that, overall, the free-to-enter fan zone operated at one-third of its 114,000 seat capacity.
Despite the empty seats, Glasgow Life, which coordinated the project, claimed the big screens had helped forge an "unforgettable" month of football.
A spokesperson for Uefa Euro 2020 Glasgow said they were “disappointed” in the turnout, but said tickets for the zone were fully booked ahead of the tournament.
They said that while each ticket provided a table that could seat up to six people, many attendees did not come in groups that large - while others did not turn up at all.
“We know from previous experience that free tickets lead to a higher than usual level of 'no shows'”, the spokesperson explained.
“Outwith Scotland match days, this was in the region of a third at each session.
"We consistently encouraged ticket holders who no longer wished to use tickets to return them to the ticketing agency so they could be rebooked by other members of the public.
“We are disappointed that the response to this ongoing request was minimal."
They added: "Unfortunately, given the necessary requirement for information on attendees for Test & Protect purposes to be captured through the ticket booking system, we were unable to change the admissions policy to allow 'walk ups'."
Plans for the fan zone ahead of the Euros was condemned by figures in Scotland’s hospitality sector, as well as by opposition MSPs, who argued it was not fair for it to open while restaurants, bars and theatres were forced to operate under tighter Covid restrictions.
But the 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.
In total, 74,000 seats in the zone sat empty during the Euros 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.
Billy Garrett, director of sport and events at Glasgow Life, described the atmosphere that evening as “absolutely electric.”
“That was the fan zone at its most alive and its most populated,” he added.
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’.