A study by governing body Uefa showed the Covid-19 pandemic cost European clubs seven billion euros ($7.91bn) across two seasons even as player wages at top sides rose by 2% to 11.9bn euros ($13.45bn) during the period.
Top-flight clubs suffered losses worth four billion euros ($4.52bn) in 2021, up from three billion euros ($3.39bn) the previous year.
The majority of losses came due to empty stadiums, with revenues from ticket sales falling by 88% in 2020-21.
Transfer revenues also took a tumble, dropping by 40%.
British media said the report, which included 724 clubs across 54 top divisions in Europe, added that 900m euros ($1.02bn) was given in rebates to broadcasters, while sponsorship revenue plummeted by 1.7bn euros ($1.92bn).
Uefa President Aleksander Ceferin, however, said there was reason for optimism with fans returning to stadiums.