Born on 26 July 1948 in Barcelona, Spain, Mons. Joseph Maria Bonnemain grew up there as a Swiss citizen abroad and completed his schooling in 1967. He then moved to Switzerland to study medicine at the University of Zurich. After graduating, he went to Rome in October 1975 to pursue studies in philosophy and theology. He was ordained a priest of the Prelature of Opus Dei on 15 August 1978 by Cardinal Franz König and celebrated his first Mass in the parish of St. Anton in Zurich.
Alongside his theological and canonical studies, he provided spiritual care to workers and farmers in the Navarre region of Spain and also served for two years as a university chaplain. In 1980, he obtained a degree in canon law and returned to Zurich, where he worked as a student chaplain until 1989, overseeing student residences and leading retreats and adult formation initiatives.
In 1985, he was appointed chaplain of Limmattal Hospital in Schlieren, a role he carried out until his episcopal appointment, dedicating himself to the pastoral care of the sick. From 1983 to 1991, he was a member of the Holy See’s delegation to the World Health Organization in Geneva. Appointed diocesan judge in 1981, he became vice judicial vicar of the Diocese of Chur in 1982 and judicial vicar in 1989.
He was named a canon of the cathedral chapter in 2003 and later held several responsibilities, including episcopal vicar and member of the diocesan council. In 2009, he was appointed Chaplain of His Holiness (Monsignor). Since 2002, he has been closely involved in the Swiss Bishops’ Conference commission on sexual abuse in the Church, serving as its secretary.
He was appointed Bishop of Chur on 15 February 2021 and received episcopal consecration on 19 March 2021. He is also Vice-President of the Swiss Bishops’ Conference and, since 2024, serves as the Swiss delegated bishop (Observer) to the Assembly of COMECE.