Prime Minister Scott Morrison said $70 million of defensive support would be provided to Ukraine, which would include missiles and ammunition.
A further $35 million would be spent on humanitarian assistance such as shelter, food and medical care.
The decision came following a meeting of federal cabinet's national security committee on Tuesday.
Mr Morrison said the majority of the defensive support to Ukraine would be lethal aid and distributed through a partnership with NATO.
However, he would not provide specifics on what weapons, or the amount of weapons, that would be sent to Ukraine due to national security concerns.
"I don't plan to give the Russian government a heads up about what is coming their way, but I can assure them it is coming your way," he told reporters in Canberra.
"We will be answering the call from (Ukrainian) President Zelenskyy. He said, 'Don't give me a ride, give me ammunition', and that is exactly what the Australian government has agreed to do."
The prime minister said the $35 million in humanitarian support, which would be provided to international organisations, would be the "opening contribution" from Australia.
Mr Morrison said it was expected there would be further requests made over time, and welcomed efforts from other countries to impose sanctions on Russia and its government following the Ukrainian invasion.
He said while the sanctions were working and having a serious impact on Russian progress, it was expected to lead to more aggression.
"It is also likely to lead to an even more violent response from Russia," he said.
"Anyone who thinks the Russian government is just going to sit there, I think, doesn't understand the intent and the outrageous objective of President Putin."
All outstanding visa applications for Ukrainians looking to come to Australia have been processed, the prime minister said.
About 100 applications are being received per day, which are being processed as the top priority due to the unfolding situation.
Mr Morrison said options were being prepared to support broader humanitarian efforts.
"We want to ensure we can provide the temporary refuge."
Opposition Leader Anthony Albanese said earlier on Tuesday there was bipartisan support for action taken against Russian aggression.
"It's important that there be a single direction going forward, as there has been up to this point, we would support any government action," he told reporters in Melbourne.
The Labor leader said the opposition strongly supported the sanctions Australia had carried out against Russia, alongside international partners such as the United States, United Kingdom and European Union.
Opposition home affairs spokeswoman Kristina Keneally said Labor supported the actions of increased military support from Australia to Ukraine.
"This is a fast-moving situation, one provoked by Russia and upends the international order that has prevailed since the end of World War II," she told Sky News.
Defence Minister Peter Dutton told reporters in Canberra that Russian forces would become more intense as they move towards the capital of Kyiv.
"Many people will die unless President Putin changes the action of the course he is on at the moment," he said.
The Sydney Opera House will be lit up in the colours of the Ukrainian flag on Tuesday night.
It follows Parliament House in Canberra being lit up in the colours of the flag on Monday night in solidarity with Ukraine.
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