About 20 people and a couple of local firefighters attended the event at Queens Park, organised by the local Extinction Rebellion group.
A minute’s silence was observed after speeches from local activists.
Millions of hectares are burning at present in Australia, where 28 people and about 480 million animals have died.
Organiser Raylene Carston said the group was devastated by the loss of lives there and decided to act.
They organised the event, at which a book was provided for people to write messages in for the residents of Mallacoota and information was made available about the charities which are supporting those affected.
"I was so upset by what I was seeing on the news ... I felt I had to do something," she said.
Invercargill Senior Station Officer Duane Shannon said it was important to recognise the work of the firefighters but also thank all people who were "going far beyond to help the neighbours".
Extinction Rebellion members Lori Johnston and Sandy Byers-Evitt decided to wear kangaroo and koala costumes during the event.
"There has been so many losses of animals there that it is absolutely heartbreaking ... The animals are defenceless. The scale of losses are enormous and will take generations to recover, so that’s why I’m dressing as a kangaroo because I’m standing with the animals," Ms Johnston said.
