In 1917, after another period of pastoral work, Hinsley became a domestic prelate of his holiness (14 November) and the rector of the English College in Rome, a post in which he remained until 1928.

Hinsley received his episcopal consecration on the following 30 November from Rafael Cardinal Merry del Val, with Archbishop Giuseppe Palica and Bishop Peter Amigo serving as co-consecrators, in the chapel of the English College.

Archbishop Hinsley, as he now was, retired as apostolic delegate due to ill health on 25 March 1934 and, in recognition of his long service on behalf of the Holy See, was appointed a canon of St. Peter's Basilica.

From this semi-retired position, Hinsley was surprisingly nominated as Archbishop of Westminster on 1 April 1935, thus becoming the spiritual leader of the Catholic Church in England and Wales.

A supporter of ecumenism,[2] Hinsley founded the multi-denominational Sword of the Spirit in October 1940 to rally his fellow English clergymen (including non-Catholics) against totalitarianism.

Hinsley wrote a shrewd letter to The Times, stressing President Roosevelt's commitment to freedom of conscience and arguing that Catholic schools should not be bullied by the state as they often provided for the poorest inner-city communities.

[8] Cardinal Hinsley, nearly blind and deaf, died from a heart attack[2] at his country retreat of Hare Street House near Buntingford, at age 77.