From 1998 to 2005, while out of politics, Mitchell joined CIBC Wood Gundy as an investment advisor.
Mitchell was first elected to the Alberta legislature as the Liberal MLA for Edmonton Meadowlark in 1986.
On March 24, 2005, he was appointed to the Canadian Senate by Governor General Adrienne Clarkson, on the advice of Prime Minister Paul Martin, where he represented Edmonton.
Mitchell served on three Senate committees: National Finance; Legal and Constitutional Affairs; and Agriculture and Forestry.
[4] On November 29, 2019, the Prime Minister's Office announced[5] that Senator Harder would step down from his position as Representative of the Government in the Senate effective December 31, 2019, and that Mitchell would step down as Government Liaison[5] but continue in the role until Harder's successor was named in "due course.