Fehr, a tough negotiator who oversaw baseball's players association for 26 years before stepping down in 2009, had been operating as an unpaid consultant for the NHLPA.
The 62-year-old lawyer takes over an organization that has been plagued by infighting and scandals and without a leader for more than a year.
"I am both humbled and honored by the expression of confidence that the players' vote reflects," said Fehr in a statement released by the NHLPA. "I'm looking forward to working closely with the membership and the executive board."
With the current Collective Bargaining Agreement set to expire on September 15, 2012, Fehr's top priorities will be to get familiar with the sport and players before rebuilding the NHLPA.
"We are pleased that the leadership position at the Players' Association has been filled, and we look forward to working with Don in his new role," said NHL Commissioner Gary Bettman.
Fehr brings a hard-nosed negotiating style to his new post.
During his years in charge of the MLBPA, the baseball union earned a reputation as the most powerful in sport with Fehr playing a major role in the 1994-95 strike that resulted in the cancellation of the World Series.
(Writing by Steve Keating in Pittsburgh, Editing by Peter Rutherford)
