WASHINGTON—Boxing champ Floyd Mayweather Jr. and music impresario DJ Khaled on Thursday became the first celebrities to face punishment over their roles in touting cryptocurrency deals that regulators say were fraudulent.

Mr. Mayweather was paid $100,000 to endorse a coin offering promoted by three men who now face civil and criminal securities-fraud charges. DJ Khaled was paid $50,000 to promote the same digital coin, known as Centra, according to the Securities and Exchange Commission.

Mr. Mayweather agreed to a $300,000 fine and to forfeit an additional $300,000 representing his gains from touting Centra and two other token sales, the SEC said. DJ Khaled will give up the $50,000 he earned and will pay a $100,000 penalty, according to the SEC.

Attorneys for Mr. Mayweather didn’t immediately respond to requests for comment. An attorney for DJ Khaled declined to comment.

Celebrity endorsements helped create buzz last year that many cryptocurrency startups used to raise money for software projects. The high-profile hype helped the startups connect with traders looking for the kind of stratospheric returns that bitcoin generated in 2017.