A malnourished emperor penguin that made international news when it landed on Western Australia's southern coast at the start of the month has been released back to the ocean with the hope it will swim back to Antarctica.

The penguin was found by local surfers at Ocean Beach, 430 kilometres south of Perth, on November 1.

The Antarctic species has been known to swim up to 1,600km on foraging trips, however this penguin was more than 3,000km from home.

The penguin, which has gained the nickname Gus after Roman emperor Augustus, was taken into the care of local seabird carer Carol Biddulph.

Adult male emperor penguins can weigh up to 40 kilograms, however Gus weighed only 23kg.

Ms Biddulph said during the 20 days she cared for him Gus recovered considerably.

"The bird had put on a reasonable amount of weight," Ms Biddulph said.

"The plumage was wonderful, well waterproofed, we had got the salt gland pumping.

"Sea birds have a salt gland so they can process the salt water."

On Wednesday, after passing a veterinary check, the penguin was released from a boat off the southern coast of Western Australia.

After jumping off the boat, Ms Biddulph said Gus turned to look at her one more time.

"Then, oh my gosh, he was just under the waves and off. But gee it was a great feeling.

"This bird had a desire to live."

Ms Biddulph said she was optimistic about Gus' journey home.

"I've got every faith he will get home," she said.

"I mean, he got here."

The animal is the first emperor penguin to be recorded in Australia.

WA's Parks and Wildlife Service said the animal was not fitted with a tracker.

The service is asking members of the public to report any further sighting of the emperor penguin to the Wildcare Helpline on 08 9474 9055.