The new laws expand background checks to include purchases and transfers between private parties and online sales.
It closes a loophole that had exempted firearms sales at gun shows from background checks, and also limits the size of ammunition magazines to 15 rounds and eight shot gun shells.
The legislation is especially significant in light of the state's history of gun violence: 14 years ago in Columbine and eight months ago in Aurora.
And just hours before the bills were signed, Colorado's Department of Corrections Executive Director, Tom Clements, was gunned down as he answered the door to his home in Monument, a south of Denver.
The hunt for his killer is underway.
Governor Hickenlooper, on this monumental day of legislation, was visibly shaken by Clements death.
"I think it's a coincidence but incredibly tragic and sad coincidence that we have to process all this in single day," said Hickenlooper.
The gun law measures were introduced in the democratic controlled state legislature early this year and passed quickly, putting Colorado among states in the front of the national gun control debate.