After following his brother Clarence "Spot" Horder to South Sydney, Harold, in his first game, stepped and swerved through the entire Glebe team in a 90-metre dash to score one of the greatest individual tries in rugby league history.

The Gregory's reference records that, in the 1912 City Cup-tie against Glebe, Harold induced the Souths selectors to name his relatively inexperienced brother Clarrie in the side.

Horder scored 20 individual points in Norths' 1922 grand final win which consisted of 2 tries and 7 goals.

In 1925, Harold moved to the Brisbane rugby league club Coorparoo as their captain coach for two seasons after leaving Souths.

Horder was inducted into the Australian Rugby League Hall of Fame on 7 September 2004 at the Dally M Awards in Sydney.