Chelsea were fined a total of €31 million ($36.5 million) for breaking financial monitoring rules by UEFA on Friday to hit a record sum for a European club penalized in a single season.
Barcelona also were ordered to pay €15 million ($17.7 million) for making excessive losses according to UEFA's complex evaluations of club accounts if they qualify for European competitions, designed to promote stability in the industry.
Both clubs were sanctioned over their financial accounts for 2024 and must pay tens of millions of more euros (dollars) in future seasons if they miss financial targets set by UEFA.
Chelsea were fined €20 million ($23.6 million) for failing to approach break-even and a further €11 million ($13 million) for spending more than a 80% set limit of its revenue on so-called "squad cost" such as transfers and wages.
"The club has worked closely and transparently with UEFA to provide a full and detailed breakdown of its financial reporting, which indicates that the financial performance of the club is on a strong upwards trajectory," Chelsea said in a statement.
"Chelsea FC greatly values its relationship with UEFA and considered it important to bring this matter to a swift conclusion by entering into a settlement agreement."
The Premier League club had been under investigation for the £76.5 million ($104.4 million) sale of two hotels between subsidiaries of Chelsea's holding company, Blueco 22 Ltd. Chelsea has been owned since 2022 by United States businessman Todd Boehly and Clearlake Capital.
Chelsea have consistently spent lavishly in the transfer market in the Boehly era.
Chelsea's biggest fine matches the record €20 million ($23.6 million) sanction imposed in 2014 on Manchester City and Paris Saint-Germain by UEFA.
Those were the first round of penalties in the system then called Financial Fair Play.
In 2023, during the first year of Boehly's ownership, Chelsea also paid UEFA a 10 million euros ($11.8 million) fine to settle irregularities committed while the club was owned by Roman Abramovich. The oligarch was forced to sell the club after Russia's military invasion of Ukraine.
Barcelona previously paid UEFA a €500,000 (590,000) fine in a 2023 case for misrepresenting income.
Both Chelsea and LaLiga winners Barcelona have qualified for the Champions League next season, which should earn both tens of millions of euros.
In other investigations settled Friday, UEFA ordered Aston Villa to pay a total of €11 million ($13 million) for excessive spending during a season it played in Europe's third-tier Conference League. Villa played in the Champions League this season.
UEFA also fined financially troubled French club Lyon €12.5 million ($14.7 million), with future fines conditional on meeting targets.
The club, owned by American businessman John Textor, is fighting an appeal case next week against being demoted from Ligue 1 amid its financial turmoil, and could yet be excluded by UEFA from the Europa League next season.
Information from The Associated Press, Reuters and ESPN's Mark Ogden contributed to this report.