Gennady was named Archbishop of Novgorod in Moscow and placed in office on 12 December 1484, the first Novgorodian prelate not chosen by lots since 1359.

Gennady's main difficulty during his archiepiscopate, however, was rooting out the Judaizer heresy from Novgorod and also Moscow, where it had spread when several Novgorodian clergymen were transferred to the capital.

He is said to have borrowed methods from the Spanish Inquisition, admiring how the King of Spain had dealt with heterodoxy in his kingdom, and he burned several heretics with the support of the grand prince and metropolitan.

[2] The Novgorodian Fourth Chronicle notes that Gennady also helped pay for one third of the reconstruction of the current Detinets or Kremlin walls between 1484 and 1490,[3] and in 1492, he calculated Easter for the next thousand years.

[citation needed] This would have had dire consequences, not only for the performance of religious rituals, but also in determining when to plant and harvest crops, and could potentially have led to famine.