Alia Joy is just weeks old but she's already made Australian political history.

The daughter of Greens co-deputy leader Larissa Waters graced the floor of the Senate on Tuesday becoming the first baby to be breastfed in the chamber.

Greens co-deputy leader Larissa Waters soothes baby Alia Joy after breastfeeding her in the Senate. Credit:AAP

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.