Zachary built the original church of Santa Maria sopra Minerva, forbade the traffic of slaves in Rome, negotiated peace with the Lombards, and sanctioned Pepin the Short's usurpation of the Frankish throne from Childeric III.

Out of respect for Zachary the king restored to the church of Rome all the territory seized by the Lombards and sent back the captives without ransom.

[4] The contemporary history (Liber pontificalis) dwells chiefly on Zachary's personal influence with Liutprand, and with his successor Ratchis.

[3] Zachary corresponded with Archbishop Boniface of Mainz,[5] counseling him about dealing with disreputable prelates such as Milo, bishop of Reims and Trier.

In 742 he appointed Boniface as papal legate to the Concilium Germanicum, hosted by Carloman, one of the Frankish mayors of the Palace.

He also restored the decaying Lateran Palace, moving the relic of the head of Saint George to the church of San Giorgio al Velabro.