Alia Joy is just weeks old but she's already made Australian political history.
Senator Waters returned to parliament for the first time since giving birth to her second daughter earlier this year, bringing the baby in for a feed during a vote on a Greens motion.
"So proud that my daughter Alia is the first baby to be breastfed in the federal Parliament! We need more #women & parents in Parli," she wrote on Twitter.
Labor frontbencher 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."
The milestone comes after Senator Waters instigated changes to Senate rules last year, extending rules that already allowed breastfeeding in the chamber to allow new mums and dads to briefly care for their infants on the floor of parliament.
The House of Representatives has made similar changes.
It followed another historic achievement in the Senate on Tuesday morning, with the swearing-in of new independent senator Lucy Gichuhi, the first black African member of the Australian parliament.
Greens colleague Sarah Hanson-Young made headlines back in 2009 when her two-year-old daughter Kora was taken from her arms and ejected from the Senate chamber.
