Horacio Miranda represented the Philippines at three editions of the Olympic rapid-fire pistol, 25 metres sport shooting competition, placing 53rd, 48th, and 54th in 1960, 1964, and 1968 respectively. He was also seventh in that event at the 1962 Asian Games, but won two medals at the 1966 edition: silver in the 30 metre rapid-fire pistol team competition (with his brother Paterno, Raymundo Quitoriano, and the non-Olympian Nestor de Castro) and bronze in the 25 metre version (alongside Edgar Bond and the non-Olympians Antonio Arguelles and Moises Gines). His brother Paterno also took part in the 25 metre event at the 1964 and 1968 Olympics.