Baby Gammy, who was born with Down's syndrome to a surrogate mother in Thailand, has been granted Australian citizenship, local media report.
Gammy was left behind while his twin sister Pipah went home with Australian parents David and Wendy Farnell last year.
The case sparked intense debate over international surrogacy agreements.
Surrogate mother Pattaramon Chanbua said she sought Australian citizenship to safeguard Gammy's future.
Gammy, who turned one in December, is eligible for Australian citizenship because David Farnell is his biological father.
He will now have access to healthcare in Australia and is eligible for an Australian passport.
The Farnells faced heavy criticism for leaving one baby behind and taking the other. Besides Down's syndrome Gammy has a congenital heart condition.
Ms Chanbua, the 21-years-old surrogate mother, claimed that the Farnells wanted Gammy aborted when they found out he had Down's syndrome, but that was against her Buddhist beliefs.
In a TV interview, the Farnells said after Gammy was born, they wanted to bring both infants home.
Ms Chanbua told the Associated Press that she had then not allowed Gammy to go with them.
It was later revealed that David Farnell had child sex convictions, prompting Australia's Department of Child Protection to launch an investigation in August.
The Farnells retain custody of Pipah but with strict court conditions, according to Australian media reports.
Gammy's case drew donations from around the world which are being managed by an Australian charity and have been used to pay for his hospital bills and a new home for Ms Chanbua's family.