The antelope, born on June 15, is a half-sister of mountain bongo Molly, born at the zoo in April. The two youngsters share a father, named Franek, but have a different mother.
The antelope sisters have not met yet but have seen each other through a metal fence separating their enclosures, Warsaw Zoo staff told Reuters.
The zoo proposed four names for the baby mountain bongo, each starting with the letter M, and asked the public to vote for their favourite one on social media.
Mountain bongos, the largest among African forest antelopes, are a critically endangered species with only about 70-80 adults left in the wild, according to the IUCN's Red List of Threatened Species.
The animals are nocturnal and have a striking appearance due to their long horns and their reddish-brown coat offset with white or yellow markings in the form of thin vertical lines.