Ken Holland, Oilers general manager and president of hockey operations, will report to Nicholson and will continue to have full autonomy over all aspects of the team's hockey operations.
The Oilers also hired Tom Anselmi, the former president and CEO of the Ottawa Senators and former chief operating officer of Maple Leaf Sports and Entertainment, to oversee the business side.
Anselmi will occupy the role of COO and president of business operations with Edmonton.
Nicholson has been Oilers CEO since April 2015 and has served as a vice chair since the team first hired him in June 2014.
Wayne Gretzky and Kevin Lowe also hold vice chair positions with the organization.
Nicholson oversaw Edmonton's hockey operations department from the time that former general manager Peter Chiarelli was fired in late January until Holland was hired in early May.
At his introductory news conference, Holland revealed Ken Hitchcock wouldn't be back as Oilers head coach. Dave Tippett was hired to succeed him three weeks later.