Johannesburg Zoo is a medium-sized city zoo with a decent collection of African animals, big cats, primates, and some exotics. Expect a straightforward, old-school zoo experience: paved paths, shaded areas, and decent enclosures that vary in quality. It's not a safari park so don't expect huge habitats or the thrill of seeing animals in the wild. Most visitors spend 2-3 hours here. The bird show and sea lion presentations are the liveliest parts; the rest is calm and a bit dated.
Best time to visit is during the cooler, drier months from May to September when temperatures are comfortable and animals are more active. Avoid midday in summer (December-February) as it gets very hot and many animals hide. Expect to pay around R150-250 per adult, with cheaper rates for kids and locals. Add a bit more for parking and snacks.
Pick the big cat and primate areas plus the African plains section; skip the small reptile house and dated elephant enclosure if you're short on time or energy. Bring your own water and hat - the paths can feel long in the sun. It's a pleasant half-day if you're in Jo'burg with kids or have a genuine interest in zoos, but not worth a special trip if you're mainly here for wildlife safaris.