Hickenlooper is a member of the gun control group Mayors Against Illegal Guns, an organization formed in 2006 and co-chaired by former New York City mayor Michael Bloomberg and former Boston mayor Thomas Menino.
On May 22, 2013, Hickenlooper granted an indefinite stay of execution to Nathan Dunlap, who was facing execution for the 1993 murder of four employees at a Chuck E. Cheese restaurant.