Hoy was a graduate of the Ohio School for the Deaf in Columbus, Ohio. He started his career at the age of twenty-four in 1886, and played in the major leagues until 1902. He played most of his career with the Washington Nationals (of the National League, not to be confused with the American League's later Washington Senators or today's NL Washington Nationals), the NL's Louisville Colonels, and the Cincinnati Reds.

In Hoy's time, the word "dumb" was used to describe someone who could not speak (as most deaf people at the time could not), rather than someone who was stupid; but since the ability to speak was often unfairly connected to one's intelligence, the epithets "dumb" and "dummy" became interchangeable with stupidity. Hoy, said to have been able to speak with a voice that resembled a squeak, was actually one of the most intelligent players of his time, and is often credited with developing the hand signals used by the umpires in the game to this day, though this credit is sometimes disputed. For this reason, as well as his all-around play -- he was a fine hitter, runner and fielder by the standards of his day -- there is a movement to have him inducted into the Baseball Hall of Fame in Cooperstown, New York.

Hoy was inducted into the Cincinnati Reds Hall of Fame in 2003. In October, 1961, at the age of 99 and just two months before his death, the Reds brought him back to Crosley Field, built on the site of his former home field, to throw out the first ball before a World Series game. He could see, if not hear, the standing ovation he received. Until the 1980s, he was believed to have been the longest-lived former player ever.