Beefalo constitutes a hybrid offspring of domestic cattle (Bos taurus), usually a male, and the American bison (Bison bison), usually a female, in managed breeding programs. The breed was created to combine the characteristics of both animals for beef production.

Beefalo are primarily cattle in genetics and appearance, with the breed association defining a full Beefalo as one with three-eighths (37.5%) bison genetics, while animals with higher percentages of bison genetics are called bison hybrids. However, genomic analysis has found that the vast majority of Beefalo, even those considered pedigree by the breed association, have no detectable bison ancestry, with no sampled Beefalo having higher than 18% bison ancestry, with most Beefalo consisting of a mixture of taurine cattle and zebu cattle ancestry.

Accidental crosses were noticed as long ago as 1749 in the Southern Colonies of North America, during British colonization. Cattle and bison were first intentionally crossbred during the mid-19th century.

One of the first efforts to cross-breed bison and domestic cattle was in 1815 by Robert Wickliffe of Lexington, Kentucky. Mr. Wickliffe's experiments continued for up to 30 years.

Another early deliberate attempt to cross-breed bison with cattle was made by Colonel Samuel Bedson, warden of Stoney Mountain Penitentiary, Winnipeg, in 1880. Bedson bought eight bison from a captive herd of James McKay and inter-bred them with Durham cattle. The hybrids raised by Bedson were described by naturalist Ernest Thompson Seton:

The hybrid animal is [claimed] to be a great improvement on both of its progenitors, as it is more docile and a better milker than the Buffalo, but retains its hardihood, while the robe is finer, darker and more even, and the general shape of the animal is improved by the reduction of the hump and increased proportion of the hind-quarters.

After seeing thousands of cattle die in a blizzard in 1886, Charles "Buffalo" Jones, a co-founder of Garden City, Kansas, also worked to cross bison and cattle at a ranch near the future Grand Canyon National Park, with the hope the animals could survive the harsh winters. He called the result "cattalo" in 1888. Mossom Martin Boyd of Bobcaygeon, Ontario first started the practice in Canada, publishing about some of his outcomes in the Journal of Heredity. After his death in 1914, the Canadian government continued experiments in crossbreeding up to 1964, with little success. For example, in 1936 the Canadian government had successfully cross-bred only 30 cattalos.

It was found early on that crossing a male bison with a domestic cow would produce few offspring, but that crossing a domestic bull with a bison cow apparently solved the problem. The female offspring proved fertile, but rarely so for the males. Although the cattalo performed well, the mating problems meant the breeder had to maintain a herd of wild and difficult-to-handle bison cows.^{[citation needed]}