Brian was born in the Manchester, UK in January 1929 but moved to Ireland in 1939 where he was enrolled in Colaiste Mhuire in Dublin. After leaving school he initially studied to join the priesthood but quickly discovered this was not the life for him and left to become a commercial traveller. In 1955 he enrolled in UCD and later graduated. While attending Harvard University in the United States on a scholarship grant he met Marie Therese whom he married in April 1955.
Paralleled with an academic career he was writing for the Irish Press newspaper and commentating on events of the day on Radio Eireann. He joined the television service when it opened in 1962 and remained an integral part of the stations current affair output until his retirement on 2004. He presented many news and analysis programmes including Broadsheet, '7 Days', 'Frontline' and 'Primetime'. He was the main anchor for the stations election and budgets coverage and was lead commentator on many of the State events including funerals and heads of state visits. He covered 10 general election campaigns and counts for RTE TV.
On RTE TV’s first full day of transmission January 1st 1962, Brian Farrell appeared as a presenter of the current affairs programme ‘Broadsheet’. In 1966 he began lecturing in UCDs Department of Politics but also in that year he along with Brian Cleeve and John O’Donoghue began presenting the current affairs programme ‘7 Days’ on RTE Television. The show continued until 1976. In October 1980 ‘Today Tonight’ began with Farrell as the main presenter. Today Tonight stayed on air until August 1992 when a number of separate programmes replaced that main current affairs output. In 1993 and 1994 he began hosting a half hour interview show broadcast on Sunday evenings at 6.30pm titled ‘Farrell’. In 1992 RTE again began providing one main current affairs programme titled 'Primetime'. Brian did not join 'Primetime' until 1997 and then stayed with the show until his retirement in 2004.
In 1968 Brian won the first of two Jacobs Award for his hosting of the 7 Days programme while a second arrived for his coverage of the 1977 General Election results programme. In 1979 he was RTE’s main anchor for their extensive live coverage of Pope John Paul II’s three day visit to Ireland.
In 1983 one of his many book published was a biography of former Fianna Fail Taoiseach Sean Lemass.
In 1994 Brian announced that he was leaving his post of Professor in the Politics Department of UCD to take up the post of Director General of the Institute of European Affairs.
He served as chairman for a number of years until 2000 as Chairman of the Arts Council.