He was born in Venice into a relatively poor, but noble Grimani family and in his early years he worked as a tradesman, soon becoming one of the most important ones in the city.

In 1494 he was created capitano generale da mar (sea commander-in-chief), a relatively easy task as he had to lead the Venetian operations along the Adriatic coast in a peaceful period.

But when in 1499 a new war between Venice and the Ottoman Empire broke out, his lack of experience led to two crushing defeats (Sapienza, 19 August, and Zonchio, six days later).

His political ties soon gained him important administrative charges and created the basis for his future election as doge (6 July 1521).

Following the French defeat at the Battle of Bicocca, however, he grew concerned about the course of the war; but he died in 1523, and it was left to his successor, Andrea Gritti, to achieve a settlement with Charles V, Holy Roman Emperor.