The All Blacks centre was suspended for a dangerous tackle on Anthony Watson during the second Test against the British and Irish Lions last month.
World Rugby initially ruled that the dual-code powerhouse would not be available to face the Wallabies in Sydney on August 19, as that would serve as the last installment of his ban.
New Zealand Rugby argued that the world champions' match of two halves against Taranaki and Counties Manukau should count as one of the four "meaningful matches" he must miss.
The governing body has now ruled in favour of Williams.
