The plaintiffs claim that his endorsement led them to make loss-making investments.
They are seeking more than $1 billion in damages.
In November 2022, Binance announced the first "CR7" token (NFT) collection in partnership with Ronaldo, which the footballer said would reward his fans.
NFTs are virtual assets that can be bought and sold but have no form of their own in the real world - in other words, they exist only in the digital environment.
They are often used to mark ownership of something online, such as a picture or video.
"CR7" represents the initials of Ronaldo's first and last name and his shirt number.
In a social media video announcing his partnership with Binance, Ronaldo encouraged his millions of followers by telling prospective investors, "We will change the game of NFT and take soccer to the next level."
On November 27, a class action was filed in the U.S. District Court for the state of Florida, stating that Ronaldo "encouraged, assisted and actively participated in the sale of unregistered securities by partnering with Binance."
The plaintiffs stated that Ronaldo's promotion of Binance led to a "500 percent increase in searches" for the crypto exchange registered in the Cayman Islands in the first weeks, which misled them.
