Nine elephants were found dead with their tusks removed from the carcasses.
Five lions also died but officials said their skins were not taken, suggesting they were accidental victims of the poisoning.
The incidents are the first of their type on record and tests are being carried out to determine the nature of the chemicals used.
A spokeswoman for the Zimbabwe Parks and Wildlife Management Authority, Caroline Washaya Moyo, said two buffalo were also killed, as were vultures that had eaten the dead animals.
Ms Washaya Moyo said the parks authority had deployed teams in the affected game reserves to investigate the poisoning.
Zimbabwe has been battling to curb poaching, which has mainly targeted rhinoceros and elephants for their horns and tusks.
Ten rhinos have been killed in Zimbabwe by poachers so far this year.
The crime is driven by booming demand for rhino horn in Asia, where it is believed to have medicinal properties, despite ample scientific evidence to the contrary.
Conservationists have warned that rhino populations are facing their worst poaching crisis for decades, especially in South Africa, Zimbabwe and Kenya.
In May, authorities in Kenya seized more than one tonne of ivory at Nairobi's international airport.
About 115 elephant tusks were found inside metal containers by sniffer dogs. Source