The zoo welcomed the newest member of its hippo herd on August 13 after a birth without any complications, biologist Kristijan Ovari said.
New mother Julka has since been protecting the baby and zookeepers have not been able to come closer to determine its sex.
In sunny Belgrade weather, visitors had the chance to watch the baby's first steps at the outside enclosure by the swimming pool.
However, the baby's father was protectively separated from the family as he could accidentally hurt the newborn, Ovari told Reuters.
The baby hippo, which weighs about 50 kilograms (110 pounds) is yet to be named.
For now, it spends its time cuddling with its mother and relaxing in the sunshine.