His translation of the Bible in Italian, formally approved by the papacy, was widely used in Italy for about two centuries.

Cardinal Carlo Vittorio Amedeo delle Lanze, knowing that Pope Benedict XIV desired a good version of the Bible in the contemporary Tuscan language, urged Martini to undertake the work.

He accordingly resigned the directorship and accepted from the King Charles Emmanuel III of Sardinia a state councillorship together with a pension.

In spite of some discouragement upon the decease of Benedict XIV, Martini persevered, completing the publication of the New Testament in 1771.

The whole work was approved, and Martini personally commended, by Pope Pius VI, who made him archbishop of Florence in 1781.