Born in Champaign, Illinois, Senator Kirk graduated from Winnetka's New Trier High School and attended Blackburn College and the Universidad Nacional Autónoma de México before earning a B.A (cum laude) in history from Cornell University. Senator Kirk also earned a master's degree from the London School of Economics and a law degree from Georgetown University, and has served as an intelligence officer in the Navy Reserve since 1989. 

Senator Kirk worked as a staff member for Congressman John Porter before moving to work at the World Bank and later the State Department. He practiced law at Baker & McKenzie before serving as a counsel to the House International Relations Committee. In 2000, Mark was elected to the House of Representatives where he served five terms before his election to the U.S. Senate.

In January 2012, Senator Kirk suffered an ischemic stroke and underwent surgeries at Northwestern Memorial Hospital to relieve swelling in his brain.  After nearly a year of intensive recovery and rehabilitation, Senator Kirk triumphantly returned to work by climbing the 45 steps of the U.S. Capitol on January 3, 2013.  Friends and colleagues from both sides of the aisle cheered as Senator Kirk walked up the Capitol steps. Senator Kirk reflected that his return to the Senate was one of the greatest moments of his life.

Senator Kirk currently serves on four Senate Committees: 1) Appropriations, 2) Banking, 3) HELP (Health, Education, Labor & Pensions), and 4) Aging. Senator Kirk is the Ranking Republican on the Appropriations Subcommittee for Military Construction and Veterans Affairs.