SeaWorld San Diego zookeepers are now asking the public to help name the plucky bird, who needed help leaving her shell.
An emperor penguin has hatched for the first time in 13 years at a US zoo.
SeaWorld San Diego welcomed the female chick - who needed help breaking out of her shell - on 12 September, the zoo announced on Wednesday.
"This is the most exciting thing we'll do all year, potentially all decade," said Justin Brackett, SeaWorld's birds curator, in a video provided by the park.
Where do emperor penguins live?
Listed as a near threatened species by the IUCN, the emperor penguin lives around the coast of Antarctica.
Climate change poses an existential threat to these iconic birds, the largest living penguin species, as it erodes the sea ice on which they depend.
17 emperor penguins live in a minus 5 Celsius habitat at the marine theme park and zoo where the egg was laid on 7 July, SeaWorld said.
Some 300 penguins of several species live in the zoo's penguin habitat, but SeaWorld staff took special pride in the emperor hatching, said Melissa Ramsey, SeaWorld's supervisor of birds who helped hatch the penguin.
How did zookeepers help hatch the penguin chick?
Unlike other species that produce multiple eggs a year, the emperor female lays only one egg once a year, Ramsey said in a telephone interview with Reuters.
While other penguin males and females share incubation duties, the female emperor usually returns to the sea to feed after laying the egg, leaving the male to incubate the egg for more than two months when it does not eat.
They usually mate for life, the WWF says.
But because the mother did not transfer the egg to the father, SeaWorld staff took the egg into their care and detected movement and noise coming from it on 7 September.
After 72 hours elapsed without progress, the SeaWorld team carefully poked a hole in the egg to help the bird out over the next two days, Ramsey said.
The team later determined the chick had a beak malformation that impeded its hatching, Brackett said.
SeaWorld is inviting the public to name the bird, putting three candidate names up for a vote on Instagram or via email: Pearl, Pandora and Astrid.