At the signing ceremony, Hickenlooper was surrounded by lawmakers who sponsored the bills, and relatives of mass shootings. Hickenlooper also signed requiring buyers to pay fees for background checks.
Each time he signed a bill, applause erupted from lawmakers and their guests, who included Jane Dougherty, whose sister was killed in the attack at Sandy Hook Elementary in Newtown, Conn.; Sandy Phillips, whose daughter was killed in Aurora; and Tom Mauser, whose son was killed in the 1999 Columbine shooting in Colorado.
Phillips, who lost daughter Jessica Ghawi, reminded Hickenlooper that it was the eight-month anniversary of the theater rampage.
"You've given us a real gift today," she told the governor.
Later, Phillips added: "Thank you so much. You're leading the entire country."
Dougherty thanked Hickenlooper with tears in her eyes. Mauser also expressed gratitude.
"I knew it would be a long haul," he said. "But I had faith in the people of Colorado."
Democratic Rep. Rhonda Fields, who represents the district that includes the Aurora theater, said the governor had signed "common-sense legislation."
"Gun violence is a problem nationwide, and sadly in the state of Colorado, we are all too familiar with some of these tragedies," Fields.
Lawmakers debated firearms proposals after the Columbine High School shooting, and began requiring background checks for buyers at gun shows. But nothing they did then was as sweeping as the proposals they took up this year.
This year, Colorado lawmakers succeeded while members of their party stumbled in other states.
Washington state's Democrat-controlled House failed this month to pass a universal background check bill. A bill requiring background checks at gun shows in New Mexico also stalled in that Democrat-led Legislature.
Republicans have warned that voters will punish Hickenlooper and other Democrats who voted in favor of the measures.