The boy sustained serious but non-life-threatening injuries when set upon by the dingo about 7pm on Friday at Dales Campground in Karijini National Park.
He has since been released from Tom Price Hospital, the WA Country Health Service said on Sunday.
WA Premier Mark McGowan told reporters that was "great news" as he praised the boy's mother for her bravery.
"His mother courageously fought off the dingo so she deserves our congratulations and she's obviously a very brave person," he said on Sunday.
Mr McGowan said dingo attacks were very rare and the advice from park rangers was that the animal in question, when found, would be destroyed.
Parks and Wildlife Department rangers spent Saturday trying to find and trap the wild dog.
"The safety of visitors is our number one priority," the department said in a statement.
"Due to the aggressive behaviour of the dingo and the fact that it has remained at the campground following the incident, rangers are preparing to humanely destroy the animal as soon as a safe opportunity presents."
The department wasn't aware of another attack in that part of Karijini, a rugged national park half the size of Sydney.
"Signage and information at Dales Campground warns visitors that dingoes may be present and provides dingo safety advice," it said.
The local government in the coastal town of Karratha last month warned visitors dingoes were frequently seen in Karijini and other popular national parks, and the animals may raid rubbish bags and take food from picnic tables.
"While searching for food or water dingoes may harass and intimidate people," the City of Karratha said.
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