On 4 April 1944 he was appointed apostolic administrator of Belluno e Feltre and Titular Bishop of Lydda by Pope Pius XII.

Bortignon received his episcopal consecration from Cardinal Adeodato Giovanni Piazza, OCD, on the following 14 May.

When Pope John XXIII asked Bortignon for a name for Bishop of Vittorio Veneto, the latter offered his old vicar general in Belluno, Albino Luciani, saying, "I know him ...

In 1960, he told his Vatican connections that the activities surrounding Padre Pio at San Giovanni Rotondo should merit an investigation.

He once served as the Vatican's preacher of spiritual exercises and as vice-president of the Triveneto regional Episcopal Conference.