His older brother is Brian Farrell, who was appointed secretary of the Pontifical Council for Promoting Christian Unity in the Roman Curia in 2002.

[4] Farrell was ordained to the priesthood for the Legionaries of Christ by Cardinal Eduardo Pironio in Rome at Our Lady of Guadalupe Basilica on December 24, 1978.

[6] On 28 December 2001, Pope John Paul II appointed Farrell as an auxiliary bishop of Washington with the titular see of Rusuccuru.

"[10] On 17 August 2016, Pope Francis appointed Farrell prefect of the newly established Dicastery for Laity, Family and Life in Rome.

A 2018 apostolic visitation to the Diocese of Wheeling-Charleston in West Virginia revealed that he had been using diocesan funds for these gifts and his own personal spending.

[23] According to the church's apostolic constitution, Praedicate Evangelium, the commission is responsible "1. to authorize any legal, economic or financial act that for the greater good of the Church or of persons must be kept confidential and removed from the examination and supervision of the competent entities; 2. to monitor contracts of the Holy See which by law demand confidentiality and to exercise vigilance over them.

[27] On 20 May 2024, Pope Francis appointed Farrell as special envoy to the LIII International Eucharistic Congress, that will be held on 8-15 September in Quito, Ecuador.

[28] In November, Francis appointed Farrell as sole director for the Holy See's pension fund, covering the Roman curia and the Vatican City former employees.

[29] After McCarrick was laicized in 2018 for credible allegations of sexual abuse against a minor, further reports of accusations and legal settlements emerged, dating back years.

These revelations led to public questions about whether bishops and clerics closely associated with McCarrick, including Farrell, had been aware of these accusations and settlements.

In September 2015, the Vatican announced that the World Meeting of Families (WMOF) would be held in Phoenix Park in Dublin, Ireland, in 2018.

"[38]On 16 August 2018, Cardinal Sean O'Malley, scheduled to lead a "pioneering session on child safeguarding", withdrew from the WMOF.