Mr. Horta-Osorio began his career at Credit Suisse in April of last year.
"Antonio Horta-Osorio, the chairman of global banking behemoth Credit Suisse, has resigned with immediate effect after violating Covid quarantine restrictions."
Mr. Horta-Osorio had only been with the bank for nine months when he was fired after an internal probe.
After a series of crises at Credit Suisse, the former CEO of Lloyds Banking Group joined the Swiss bank.
However, it has been revealed that he broke Covid restrictions last year, including going to the Wimbledon tennis championships.
In a statement released by the bank, Mr. Horta-Osorio said, "I apologize that a number of my personal acts have caused challenges for the bank and affected my ability to represent the bank internally and publicly."
"I think that, at this critical time, my resignation is in the best interests of the bank and its stakeholders," he added.
Axel Lehmann, a board member, has taken Mr. Horta- Osorio's seat.
When Antonio Horta-Osorio went to Wimbledon to watch Novak Djokovic win the men's singles title, he broke Covid guidelines.
Mr. Horta-Osorio had violated Covid-19 guidelines, according to a preliminary examination conducted by Credit Suisse last month.
In July, he visited the Wimbledon tennis championships while in quarantine in the UK due to Covid-19 limitations.
According to Reuters, Mr. Horta-Osorio also violated Swiss Covid rules by flying into the country on November 28 and leaving on December 1. According to Swiss law, he should have been quarantined for ten days when he arrived.
Following a succession of problems at Credit Suisse, Mr. Horta-Osorio joined the bank in April of last year.
Tidjane Thiam, the then-CEO of Credit Suisse, resigned in February 2020 when it was found that the firm had spied on key staff. Mr. Thiam claimed he was unaware of the espionage operations.
Credit Suisse has also suffered significant losses as a result of the failing financial business Greensill, which funded Liberty Steel, and Archegos, the collapsed US hedge fund last year.
Mr. Horta-Osorio started last year in a report on the company's relationship with Archegos, "We are dedicated to fostering a culture of personal responsibility and accountability."
