Leeder succeeds Roy Mlakar, who is stepping down when his contract expires at the end of the month. Mlakar, who also was chief executive officer of Senators Sports & Entertainment, spent 13 years in the front office roles.
Leeder will also serve as president of Senators Sports & Entertainment.
Erin Crowe was named executive vice president in addition to her role as chief financial officer and General Manager Bryan Murray will add the title of executive vice president.
The moves are effective July 1.
Leeder has been with the Senators since their inception in 1990. He was promoted to chief operating officer in 2002.