Born in Tucson, Arizona, he is the son of former U.S. Representative Morris "Mo" Udall. The Udall family is one of America's more prolific political families. Mark Udall graduated from Williams College in 1972 and moved to Colorado. He worked at the Colorado Outward Bound School for 20 years, including ten years as the school's executive director. He was elected to the Colorado House of Representatives in 1996. After one term he was elected to the U.S. House of Representatives, where he served five terms and worked on energy and national resources.
Udall won a competitive election for the U.S. Senate in 2008, defeating Republican challenger Bob Schaffer. He chairs the Senate Energy Subcommittee on National Parks. Udall is a prolific mountaineer and was featured in Men's Journal magazine for his athletic abilities.