The case of the H5 strain in a brown skua was confirmed on Thursday morning by the island state's environment department.
The department said the carcass of the wild seabird was found at Rocky Cape on the state's northwest coast, with the case confirmed via subsequent testing.
"I want to be clear that there is no evidence of an outbreak and there is no detection in commercial poultry at this time," Primary Industries and Water Minister Gavin Pearce said.
"We've been working closely with industry, wildlife and biosecurity experts to strengthen surveillance, preparedness and response arrangements across the state.
"I want to reassure Tasmanians that we are prepared to respond to H5 bird flu, and we will continue to provide updates as more information becomes available."
As of Wednesday night, there had been 151 confirmed H5 bird flu "events" Australia wide including SA (93), Victoria (43), WA (10), NSW (four) and Queensland (one).
There were more than 300 infections confirmed on Wednesday, a day after the federal government rolled out vaccines for captive populations of threatened birds.
The H5 strain, which arrived in Australia in June, has killed hundreds of millions of poultry worldwide and devastated wild bird and marine mammal populations.
Mr Pearce urged Tasmanians to remain vigilant and report sick or dead birds and wildlife.
The state had developed an avian influenza response plan and was working with the commercial poultry sector in relation to biosecurity.
There were also plans in place to help protect species considered most at risk, including the migratory orange-bellied parrot and Tasmanian devil, he said.
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