The city achieved this goal in May, 1884 when the museum opened to the public after having received its official charter in 1882. The museum received a strong reputation in 1890 when taxidermist and biologist Carl Akeley constructed a muskrat diorama which was the world's first complete museum habitat diorama. Akeley was recognized as the father of taxidermy and his diorama work became known as the Milwaukee style.
The museum was later moved to a new building that would house it as well as a library in 1898. A few years later in 1902, the museum added a history and anthropology department to increase its scope from primarily focusing on natural history. In 1960, construction began on the current museum building and it was completed in 1962. No major changes took place until the 1990s, when the museum renovated the lower level to add a new food court, ticketing offices, the previously mentioned theater/planetarium, and The Puelicher Butterfly Wing, which was completed in summer 2000.