On 19 May 1936, Antoniutti was appointed Apostolic Delegate to Albania and Titular Archbishop of Synnada in Phrygia by Pope Pius XI. He received his episcopal consecration on the following 29 June from Cardinal Pietro Fumasoni Biondi, with Archbishops Rossi (who by then was Latin Patriarch of Constantinople) and Costantini serving as co-consecrators, in Rome. Remaining as Albania's apostolic delegate until August 1936, Antoniutti served as a papal envoy to Spain during its civil war on 25 July 1937, for the purposes of exchanging of prisoners and providing assistance to priests who had fled from Communist areas. He was named, on the following 21 September chargé d'affaires to the Nationalist government. Antoniutti later became Apostolic Delegate to Canada on 14 July 1938. During his time in Ottawa, he described Maclean's editor Blair Fraser, the father of Graham Fraser, as "badly informed" after he accused conservative clergy of keeping the Church in Canada too old-fashioned in its social principles in an article that the Apostolic Delegate called "evidently tendentious".[1] He also presided over the controversial resignation of Archbishop Joseph Charbonneau.[2]
Seeking a period of rest in his native Nimis, Antoniutti departed from Rome on 1 August 1974, and was instantly killed when his car hit another vehicle on a bypass of Bologna. His body was moved to Nimis two days later, which would have been his seventy-sixth birthday, for a funeral Mass, which was celebrated by Cardinals Ermenegildo Florit and Albino Luciani, and nine other bishops. Antoniutti is buried at the parish church in Nimis.[citation needed]
Cardinal Antoniutti, seen as a compromise candidate for the papacy by conservative cardinals, is alleged to have received about twenty votes during one of the ballots in the conclave of 1963.[4]
As Pope Paul VI received the homage of the cardinals following his election, he asked of Antoniutti to "be a brother and a friend to me," to which the Cardinal replied, "I will always be deferent to the pope".[4]