The Matildas star tore her anterior cruciate ligament during a Chelsea training camp in January.
Rigoni had a salary of more than $2 million.
Talismanic Australian striker Sam Kerr was officially ruled out of the Olympics Tuesday, almost five months after a serious knee injury derailed her season with Chelsea."Attacker Amy Sayer (ACL) and forward Sam Kerr (ACL) remain on the sidelines with long-term injuries," the squad announcement said.
Sam Kerr, who ruptured an ACL over the winter, was ruled out of the Paris Olympics.