Lincoln Park Zoo zookeeper Kathy Schema tells HTR Media the 3½-month-old male came from Washington state, where his mother was shot and killed by a bear hunter who felt threatened by her.
The zoo was in need after its 20-year old cougar, Colleen, died about two weeks ago.
Schema says the zoo is still seeking another cub so the two can grow up together.
The zoo is having a grand re-opening Saturday, after several exhibit upgrades.
The baby cougar is off exhibit to adjust to his surroundings but Schema says he will be on display Saturday for short periods.
Other new animals include a sandhill crane, three wild turkeys and a red-tailed hawk.