Atcheynum was selected in the third round, 52nd overall, by the Hartford Whalers in the 1989 NHL Entry Draft after scoring 70 goals in 71 games with the Moose Jaw Warriors of the Western Hockey League during the 1988–89 season.
He played in 61 games (scoring a respectable 11 goals and 15 assists) during the 1997–98 NHL season for the St. Louis Blues after signing with the team as a free agent.
The main reasoning behind Atcheynum being called up to the Blues during this period was due to the lack of depth on their roster early on in the 1997-98 season.
Blues general manager Larry Pleau was impressed by Atcheynum's hard work, saying "Blair's not a player in the bottom third of our roster.
Atcheynum and Sasakamoose were recognized as role models at both the summer and winter games as hope for young First Nations athletes.