Cardinal Brady led the procession of around 2,000 through Drogheda, Co Louth, yesterday to celebrate the 90th anniversary of the beatification of the saint.
But he left it to his junior to publicly speak of the issue of clerical sex abuse.
The Cardinal was embroiled in controversy earlier this year when it emerged that he had sworn two of Fr Smyth's teenage victims to secrecy in 1975 after recording their statements in a church inquiry.
He refused to resign when the revelations emerged.
Despite being the chief celebrant, he sat on a nearby altar and listened as the homily was delivered by the Bishop of Down and Conor, Bishop Donal McKeown, who referred to recent sex abuse scandals.
Afterwards, the cardinal joined Bishop McKeown, the Auxiliary Bishop of Armagh, Bishop Gerard Clifford and parish priest of St Peter's Church, Canon James Carroll, on the steps outside to greet members of the congregation.
Dangerous
Some 429 years after the saint died in defence of his Catholic faith, an estimated crowd of 2,000 people attended yesterday's special Mass.
In his homily, Bishop McKeown maintained that Ireland was "now a more dangerous place'' for young men in particular and referred to widespread hopelessness among the young.
Quoting statistics that 188 young people had died in the care of the State in the last 10 years and reminding listeners that Ireland has one of the worst suicide rates in Europe, Bishop McKeown warned against the rising tide of despair among the country's young population.
Referring to the child sex abuse scandal, he said that the shame this brought "is nothing compared to the reality that so many lives have been permanently scarred because of pain and suffering inflicted on them. Many who were abused have lived lives marked by depression, substance abuse, huge problems in establishing healthy relationships and emotional turmoil, both when they are awake and when they sleep''.
The bishop went on to say that the "real tragedy of the current situation regarding historical child abuse in Ireland would be to let the idea go out that if Ireland kicked the church hard enough, it would have kicked child abuse in the country. With many of those who work with young people, I'd dare to suggest that Ireland is globally now a more dangerous place for young people than it was in the terrible old days that we all wish to leave behind''.
Bishop McKeown said that Oliver Plunkett's example had shown that people are capable of great things.
"The uncomfortable truth about what we are capable of as human beings -- love, faithfulness, generosity, service and forgiveness -- is not welcome in some circles which would rather have us believe the inhuman myth that only money, power and consumerism can bring us salvation. Salvation will not come from 'Celebrity Come Dancing' or the 'X Factor'. Simon Cowell is not God,'' said the bishop.
Martyred in England in 1681, Oliver Plunkett was a former Archbishop of Armagh and Primate of All Ireland, he was canonised by Pope Paul VI in 1975.
SIC: II