Still young, he accompanied a relative in France, Alvise Badoer, who had been appointed extraordinary ambassador to that kingdom on behalf of the Republic of Venice.

When he returned home, he was sent by the Republic of Venice to Charles II, Archduke of Austria, and on 1 May 1568 he was sent to the court of Emmanuel Philibert, Duke of Savoy, always as legate, leaving Turin on 29 September 1570.

[2] In June 1573 Morosini was sent to Henry of Valois to pay homage to him on behalf of the Republic of Venice in the recent success of his obtaining the Polish crown.

[3] The episcopal consecration followed on 3 November in the Venetian Church of San Giorgio Maggiore by the hands of Cesare Costa, Apostolic Nuncio to Venice.

To support the Catholic war he was allowed by the Pope to sell estates of the Church, but this was fiercely opposed by the French clergy.