Hotchkiss was born in Watertown, Connecticut, and grew up in a family involved in machinery. His father and brother, both inventors, had established a business that manufactured their patented articles. In 1856 Hotchkiss designed a rifle field gun that the Mexican government purchased. Along with his brother, Andrew, he came up with a projectile for rifled artillery. It had two sections (front and rear) made of cast iron that were joined by a band of lead, intended to fit into and take the shape of the grooves of the rifling in the gun. This created a much more accurate shell. Hotchkiss also helped his family to develop a better percussion fuse, and, as a result, more Hotchkiss shells were used for rifled cannon s during the American Civil War than any other munitions manufacturer in the country. His family was so closely associated with the Union cause that during the New York City draft riots of 1863, Hotchkiss had to ride through the streets of Manhattan concealed beneath a pile of cloth.

Success followed Hotchkiss after the war. He traveled to Paris, where he invented an improved metallic cartridge case and made many improvements in hand-held firearms and cannons. Hotchkiss designed a revolving-barrel machine gun and created a revolving cannon that destroyed a boat during trials, having hit the ship with 70 shots out of 119 fired. While aboard a train in 1875, he met a Romanian army officer who told him of the need for a magazine repeating rifle. In a half-hour, Hotchkiss sketched a design for such a weapon, which later proved to be superior to all others at the time.

Hotchkiss was reputed to be the world's best artillery engineer. By 1882, his B.B. Hotchkiss Company had branches throughout Europe. Hotchkiss was working on a new machine gun design when he died in 1885. His company perfected his plans after his death, and brought out a gas-operated machine gun which was used extensively in World War I. The Hotchkiss machine gun remained in use by the British army up until the late 1930s.