Hollingworth was ordained as an Anglican priest in 1960. Hollingworth became deacon-in-charge and then priest-in-charge of St Mary's North Melbourne, in a group ministry of the Anglican Inner City Mission within the Melbourne Diocesan Centre. In 1964 he joined the Brotherhood of St Laurence, an independent Anglican welfare organisation, as chaplain and director of youth and children's work, then as director of social policy and research. He completed a master's degree in social work and in 1980 was appointed executive director of the Brotherhood of St Laurence, where he served for 25 years and was involved in other associated community and welfare bodies.