The breed was created in the early 1980s by Cora Cobb, with the two foundation cats being Elsa, a black domestic shorthaired cat, and an unnamed blue domestic shorthair. The first mating of these two cats produced five black or blue shorthaired kittens as well as Siegfried (born 1984) who was blue with medium long hair. The second mating produced five black or blue shorthaired kittens, as well as a black longhair female and Brunhilde (born 1985), a blue longhaired female. Mrs. Cobb decided to mate Siegfried and Brunhilde, and their first litter was born in 1986. The offspring of Siegfried and Brunhilde were eventually out-crossed to natural Russian Blues in order to replicate the Russian Blue type. Although the Nebelung is sometimes called a longhaired Russian Blue, it is actually a separate breed, as the Russian Blue does not produce longhaired offspring. The Nebelung will produce both longhair and shorthair offspring in the same litter.

The breed was officially recognized by The International Cat Association (TICA) in 1987 under the 'new breeds' category. They are not recognized as a breed in the Cat Fanciers Association (CFA), or most other associations, as they mimic the natural, long established Russian Blue except for coat length.

Nebelung is a German word meaning 'creature of the mist'. These cats are judged in TICA on the same standard as a Russian Blue with the exception of their coat, which is mid-length with a dense plumy tail. They have green eyes, and their fur must be 'blue' tipped with silver.