The Queensland senator will replace Adam Bandt in a "consensus" decision of the party room.
Greens senator Larissa Waters will be fifth person to lead the federal Greens.
Larissa Waters will become the fifth leader of the Greens in the federal parliament, replacing Adam Bandt in a "consensus" decision of a smaller party room which met in Melbourne on Thursday.
Mehreen Faruqi and Sarah Hanson-Young, the other contenders for the role, will continue as deputy and as leader of business in the Senate, respectively.
The Greens lost three of their four lower house seats, but will hold the balance of power in the Senate, Senator Waters promising a "firm but constructive" approach.
Larissa Waters has been chosen as the new federal Greens leader, replacing Adam Bandt.
The Greens held a party room meeting in Melbourne on Thursday to select a leader following the shock loss of Adam Bandt.
The race was between Mehreen Faruqi, Sarah Hanson-Young and Senator Waters.
A Greens source told the ABC the role was decided by "consensus".
Senator Faruqi, who is from New South Wales, was chosen as deputy and Senator Hanson-Young, from South Australia, was chosen as manager of business in the Senate.
"I feel so strengthened by the sentiment of the room and by this amazing team," Senator Waters told reporters after the meeting.
"We've got a lot of work to do because people are really hurting and the planet is hurting, and we need a parliament that actually delivers for people and has the courage and the boldness and the heart to deliver some help to people.".
A disappointing election campaign saw the minor party lose three of its four seats in the lower house after a modest drop in its national share of the first preference vote.
But the party will again exert significant influence in the Senate, where it has retained its 11 seats and is likely to be in the balance of power, meaning Labor could pass legislation with its support alone.
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