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.
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