The former Manchester United manager died at the age of 94.
After Wilf McGuiness was sacked, the Irishman took over from Sir Matt Busby who had briefly returned to management.
During the 1971/72 season, O' Farrell led a First Division title charge at United, but they eventually fell away from the race and finished eighth.
He was fired as United manager in 1972 after a loss to Crystal Palace left the club third from the bottom in England's top flight. He won 30 out of his 81 games at Manchester United.
O' Farrell was a railway worker and a firefighter before joining the Irish side Cork United in 1947. After a year with West Ham, the left-half made his debut for the Hammers in 1950. He played for the east London club for over 200 appearances and then joined the club's rival, the club legend Sir Tom Finney.
Between 1952 and 1959 O' Farrell was capped nine times for the Republic of Ireland national team.
It was with great sadness that the Club heard the news that their former manager Frank O’Farrell died on 6 March 2022, aged 94.
Rest in peace, Frank 💙
— Leicester City (@LCFC) March 7, 2022
He turned out for the club before ending his playing days due to an injury, and then became the club's manager. He was promoted to the Third Division after four years at Torquay United.
Before he joined Manchester United, O' Farrell was the manager ofLeicester City, who lost to Manchester City in the 1969 FA Cup final, but were promoted back to the top flight in 1971.
He signed a five-year contract worth 15 grand a year, with Busby recommending O' Farrell for the role. He fell out with George Best, who was one of the players he managed. He had brief spells with Al-Shaab and the Iranian national team after he was sacked as Red Devil manager.
Having achieved so much at Torquay United, and having laid the foundations for many of its later successes, Frank O' Farrell's status as a club legend is unquestioned.
The thoughts, prayers and sympathies of everyone at the club go out to Frank's family and friends at this sad time.
In 1983, O' Farrell retired from management and went on to work as a scout and as a nurse at a nursing home.