Spaling went undrafted in the OHL after his minor midget season and signed as a free agent with the Listowel Cyclones Jr. B. club of the OHA.

After a solid season with the Cyclones, Spaling was chosen in the sixth round of 2005 OHL Priority Selection as a major midget-aged player by the Kitchener Rangers.

Spaling won the William Hanley Trophy in the 2007–08 season, awarded to the OHL's most sportsmanlike player.

[6] He attended the Predators' training camp and was later reassigned to the team's American Hockey League (AHL) affiliate, the Milwaukee Admirals.

[10] On June 27, 2014, at the 2014 NHL Entry Draft, Spaling, as an impending restricted free agent, was traded along with Patric Hörnqvist to the Pittsburgh Penguins in exchange for forward James Neal.

[15] Spaling made his Sharks debut on February 24, where he recorded a goal on his first shot, playing in his first shift with the club.

He left for Switzerland in the summer of 2016, signing a one-year deal with Genève-Servette HC of the National League (NL) in August.

[16] Spaling made his NL debut on September 23, 2016, on home ice against Fribourg-Gottéron, after missing the first 6 games with a shoulder injury.

[18] Nathan also played hockey and was a standout Canadian university player with the UOIT Ridgebacks, as well as having represented the Guelph Storm in the OHL.