Waters, from the left-wing Greens party, fed her two-month-old daughter Alia Joy during a vote in the federal Senate chamber on Tuesday, the Sydney Morning Herald reported.
The senator said on Facebook: "I am so proud that my daughter Alia is the first baby to be breastfed in the federal Parliament! And we need more family-friendly and flexible workplaces, and affordable childcare, for everyone."
Fellow politician Katy Gallagher said it was a moment that deserved to be acknowledged.
"Women have been doing it in Parliaments around the world... It is great to see it is able to occur now in the Senate," she told Sky News.
"Women are going to continue to have babies and if they want to do their job and be at work and look after their baby... the reality is we are going to have to accommodate that," she added.
The Australian House of Representatives last year joined the Senate in allowing breastfeeding, but no MP in either house had done so.
It shows a marked change in the Australian Parliament's policy from eight years ago, when Greens member Sarah Hanson-Young had her two-year-old daughter, Kora, taken from her arms and thrown out of the Senate, said the report.
The subject is a sensitive issue in many Parliaments around the world. In 2016, Spanish MP Carolina Bescansa, from the Podemos (We Can) party, was both criticised and commended for taking her baby into Parliament and breastfeeding him.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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