Melton resident and cancer survivor Barney Miller, who is based in Sunshine, said the new law paid homage to those who had died.

Mr Miller has known 12 firefighters who died from cancer.

Under the law, which passed through Federal Parliament's lower house on Thursday, if a firefighter is diagnosed with cancer it will be presumed to be work-related.

If employers and insurers reject the claim it would be left to the courts for a ruling.

A spokesman for the United Firefighters Union of Australia said firefighters had a higher risk of some cancers.

They often absorbed carcinogens through their skin as a result of thousands of toxins and gases released through a fire.

Mr Miller said the legislation, which was introduced by Melbourne Greens MP Adam Bandt, meant sick firefighters would finally have access to medical assistance and workers' compensation, removing the requirement to prove exposure to such toxins resulted in cancer.

Melton's CFA station officer Jayson Hirt said his staff fully supported the move.

"There is a significant number of older and retired firefighters who are affected by cancer. This recognises the risks we face daily," he said.

United Firefighters Union of Australia secretary Peter Marshall said 100-plus firefighters were in the Parliament's gallery to applaud the decision.

Mr Miller added: "[The government] has decided to proceed with legislation that will give comfort to those firefighters who have contracted one of the occupational cancers that is specified in the legislation.

"Peter Marshall and the union and [federal] government have done a lot of work on it. I really take my hat off to them," he said.