He had recently been injured in a fall and died in a Newcastle hospital.
Cardinal O’Brien resigned as Archbishop of St Andrews and Edinburgh in 2013 after admitting sexual misconduct.
Confirmation of his death was announced by his successor, Archbishop Leo Cushley.
He said: “At 1am on 19 March 2018, his eminence Keith Patrick Cardinal O’Brien, Archbishop Emeritus of St Andrews & Edinburgh, died at the Royal Victoria Hospital in Newcastle-upon-Tyne surrounded by family and friends and fortified by the rites of Holy Church. RIP.
“In life, Cardinal O’Brien may have divided opinion – in death, however, I think all can be united in praying for the repose of his soul, for comfort for his grieving family and that support and solace be given to those whom he offended, hurt and let down. May he rest in peace.”
His successor gave him the last rites on Friday.
The cardinal had resigned in February 2013 after three priests and a former priest alleged improper conduct during the 1980s.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.
Cardinal Keith O’Brien, formerly the Catholic Church’s most senior cleric in Britain, has died at the age of 80.