Twenty-nine of the deaths were recorded in Toamasina, the Indian Ocean island country's second-largest city, and two in a neighbouring district, the National Bureau for Risk and Disaster Management (BNGRC) said in an updated report.
Residents in and around Toamasina described scenes of chaos as the cyclone made landfall late on Tuesday.
"I have never experienced winds this violent ... The doors and windows are made of metal but they are being violently shaken," Harimanga Ranaivo said.
Gezani also left at least 36 people seriously injured.
More than 2740 residents were relocated as a precaution after the cyclone struck coastal communities before moving inland.
The cyclone's aftermath displaced another 6,870 people while a total 250,406 were classified as disaster victims, the BNGRC said.
It was the second cyclone to hit Madagascar this year, 10 days after tropical cyclone Fytia killed 14 and displaced more than 31,000 people, according to the United Nations' humanitarian office.
At its peak Gezani unleashed sustained winds of about 185 km/h, with gusts surging to nearly 270km/h - powerful enough to rip metal sheeting from rooftops and uproot large trees.
Ahead of the cyclone's arrival, officials shuttered schools and rushed to prepare emergency shelters.
The BNGRC had warned earlier that rising sea levels in Toamasina were already flooding streets.
Homes collapsed under the pressure of the winds, roofs were torn away, walls crumbled and neighbourhoods were plunged into darkness as power lines snapped.
By Wednesday morning, Madagascar's meteorological service said Gezani had weakened to a moderate tropical storm and had moved westward inland, about 100km north of the capital Antananarivo.
"Gezani will cross the central highlands from east to west today, before moving out to sea into the Mozambique Channel this evening or tonight," the service said.
