In the years after his conversion, Coughlan served as a lay preacher in England and Ireland, and for a time was a close associate of Methodist founder John Wesley.

In 1766, through the mediation of a local merchant with connections in England, a request was made to the Bishop of London to ordain Coughlan and provide for him to travel to Newfoundland.

Initially, Coughlan carried out the expected duties of an Anglican priest, performed the sacraments, established a school and chapels, and became a Justice of the Peace.

His popularity among the elite and merchant classes, however, was somewhat lacking, and this sector caused Coughlan much trouble and eventually led to his leaving Newfoundland.

His 1776 Account recounts his ministry in Newfoundland, and, while decrying the severity of the climate, displays a great affection for the "simple", "artless" people of his congregation, praising their practical "genius" despite their lack of formal education.