Mr Brennan died on Wednesday at the age of 60 after battling cancer.
Politicians, headed by former taoisigh Bertie Ahern and Albert Reynolds, formed a guard of honour as Mr Brennan’s remains were brought into the Holy Cross Church in Dundrum, Dublin.
Chief mourners at the removal were Mr Brennan’s wife Ann, his two sons Shay and Daire, and his four daughters, Aoife, Breffni, Sine and Eanna.
Among those in attendance were current and former Government ministers, members of Fianna Fáil, Fine Gael, Labour, the PDs, the Green Party and Sinn Féin and Independent TDs.
The funeral Mass will take place at midday today, followed by burial at St Nahi’s Cemetery.
Mr Brennan was one of the most popular and respected members of the Dáil. First elected in Dublin South in 1981, he retained his seat at every election, frequently topping the poll.
He was appointed a junior minister in 1987 and became a senior minister in 1989 when handed the tourism and transport portfolio.
He would go on to serve in a number of departments during a distinguished ministerial career, including education, communications, and social and family affairs.
Because of his ill health, he resigned from Government when Brian Cowen was appointed Taoiseach and was preparing his new Cabinet last May.
President McAleese led the tributes when his death was announced, saying Mr Brennan had played a “major role” in the building of modern Ireland.
“His many talents were such that he could have been successful in several fields, yet it was a mark of the man that he chose to devote those gifts to public service and the public good,” she said.
The Taoiseach said Mr Brennan would be remembered as a “brilliant political strategist, a dedicated constituency TD, a reforming minister and a very popular colleague”.