He was born in Charlottenburg, Berlin and joined the Reichswehr as a cadet in 1925. He attended a course at the cavalry school in Hanover in 1928 and was promoted to lieutenant. In 1936 he was a member of the gold medal winning German show jumping team in the equestrian event at the Berlin Summer Olympics, on his horse Alchemy.
At the outbreak of World War II he was a Hauptmann on the general staff of the Oberkommando der Wehrmacht. After serving in an infantry division he was promoted to Major in January 1941 and Oberstleutnant in April 1942. On 13 March 1943 Generalmajor Henning von Tresckow asked Brandt to carry a package containing bottles of what he claimed was cognac onto Hitler`s Condor plane for delivery to Oberst Helmuth Stieff as payment for a lost bet. The package in fact contained a primed bomb which in the event failed to detonate. In May 1943 Brandt was promoted to Oberst.
On 20 July 1944 he arrived at the Wolf`s Lair headquarters in Rastenburg, East Prussia for a situation conference attended by Hitler. With the assistance of Major Ernst John von Freyend, Oberst von Stauffenberg put a briefcase containing a primed bomb at Brandt`s feet as close as possible to Hitler and to the right of General Heusinger who was standing next to him. Brandt wanted to get a better look at a map on the table and moved the briefcase to the other side of a thick table leg. Seven minutes later the bomb exploded and blew one of Brandt`s legs off.
Brandt died the next day in Rastenburg hospital and was posthumously promoted to Generalmajor by Hitler. Three other people also died as a result of the explosion. It was later concluded that its exact positioning next to a leg of the map table was a crucial factor in determining who in the room survived.
In the 2008 film Valkyrie, Heinz Brandt is portrayed by British actor Tom Hollander, who is shown as an antagonist of Claus von Stauffenberg in the beginning of the movie.