The youngest brother of noted British marine watercolorist Charles Napier Hemy (1841-1917) and Thomas Hemy (1852-1937) also a marine painter, Bernard Hemy was born in Australia where his family had emigrated in 1852. Like both of his siblings, he later returned to his family's traditional home at Newcastle-on-Tyne where he settled to paint for the remainder of his life in North Shields.
It is likely that he studied art at the Newcastle Art School where both of his brothers attended. Unlike them however, he was not widely traveled, preferring the quieter life of the North East Coast of England. Throughout his career he displayed a strong competence at creating realistic portrayals of every day marine activity, skillfully documenting coastal and harbor views as well as local fishing scenes of the period.
Today, paintings by Bernard Benedict Hemy are scarce. He is known to have exhibited at the Suffolk Street Gallery in London in both 1875 and 1877 and was a participant in various other English exhibitions during his lifetime.