The Games' organising committee (GOLDOC) said the 23-year-old was admitted to Gold Coast University Hospital (GCUH) on Thursday.
"The patient received immediate treatment for malaria on arrival at GCUH," GOLDOC said in a statement.
"The patient remains admitted to GCUH in a serious condition and continues to be closely monitored."
The committee gave no further details, citing patient confidentiality.
The mosquito-borne disease infects around 216 million people a year worldwide, killing around half a million of them. Most deaths are among babies and young children in the poorest parts of Africa.
Mainland Australia has been malaria-free for decades.
"We have robust treatments for malaria in this country," GOLDOC said.
A number of athletes have fallen sick at the Games, including three from the same team who were quarantined for 48 hours after contracting influenza earlier in the week.
The New Zealand women's rugby sevens team was placed in isolation after one of their players was diagnosed with mumps.
(Editing by Amlan Chakraborty)
