The appeal will be heard by NHL commissioner Gary Bettman.
Wideman was given 20 games for knocking linesman Don Henderson to the ice in a Jan. 27 game against the Nashville Predators.
Wideman took a hit from Predators forward Miikka Salomaki before making his way to the Calgary bench.
Henderson had his back to Wideman, who seemed to give the official a shove as the two made contact. The 32-year-old defenceman apologized on the ice and after the game, but the league felt his actions warranted a lengthy suspension.
The NHLPA disagreed with the suspension when it was announced on Feb. 3, announcing their intent to appeal immediately.
“We strongly disagree with the League’s decision to suspend Dennis Wideman,” said an NHLPA statement. “Dennis has played in 11 NHL seasons and almost 800 games without incident. The facts, including the medical evidence presented at the hearing, clearly demonstrate that Dennis had no intention to make contact with the linesman. An appeal has been filed on the player’s behalf.”
Should the suspension be upheld, Wideman would forfeit $564,516.13 in salary to the Players’ Emergency Assistance Fund. He's already served the first two games of his ban.