Victorian MP Fiona Richardson was an "amazing campaigner against family violence" before her early death from cancer.
Ms Richardson died aged 50 on Wednesday night, just a day after revealing she had been diagnosed with multiple tumours.
"Shocked & so very sad at the loss of Fiona Richardson. An amazing campaigner against family violence. A brave and kind woman," former prime minister Julia Gillard tweeted on Thursday.
Ms Richardson became Australia's first minister for the prevention of family violence in 2014 and oversaw a ground-breaking royal commission into the issue.
Last year, Ms Richardson opened up about her own history of domestic violence at the hands of her alcoholic, abusive father in Tanzania.
"Her decision to talk about her own family's experience on Australian Story took guts," her family said in a statement.
Premier Daniel Andrews said Ms Richardson "was a person of conviction, of character, of extraordinary composure" and could never be replaced.
"Fiona fought until the very end. In fact, she only relieved herself of her parliamentary responsibilities yesterday," Mr Andrews said.
Ms Richardson joined Labor in 1991, held the seat of Northcote from 2006 and successfully fought breast cancer in 2013.
She announced she was taking a leave of absence early in August before revealing her diagnosis of multiple tumours on Tuesday.
On Twitter, federal Labor leader Bill Shorten said "we've lost a remarkable, brave and inspirational woman".
Victorian Opposition Leader Matthew Guy wrote "the sadness at Spring Street will be immense".
Federal Labor MP Tanya Plibersek said Ms Richardson had made a difference.
"Many women and their children are safer today because of Fiona's determination to change a system that had let them down for too long," she said.
One of Ms Richardson's right faction colleagues, Small Business Minister Philip Dalidakis, said she had also been the architect of Labor's suburban level crossing removal policy, one of the government's major policy successes.
"I think mostly about her husband and two young children of course who will be feeling this far more than anyone else," he told reporters.
