Kenmore South State School Grade 4 student Harper Nielsen, aged nine, was given detention for not standing when Advance Australia Fair was played in assembly.
She said she believes the lyrics "we are young" marginalises Indigenous people.
“The reason why I don’t sing it or stand is because Advance Australia Fair means advance White Australia,” she told The Courier-Mail.
“When it says we are young it completely ignores the fact that Indigenous culture was here for over 50,000 years before colonisation.”
Her father Mark said he supported Harper.
"She's shown incredible bravery in wanting to stick to what she believes in and to make a stance for what she believes is right", he told ABC radio on Wednesday.
"We couldn't be more proud of her for wanting to do this."