The award, presented by the John F. Kennedy Library Foundation, was given to Giffords Sunday by foundation President Caroline Kennedy, the Boston Globe reported.
"It's been a hard two years for me, but I want to make the world a better place," Giffords said in receiving the award at the John F. Kennedy Presidential Library and Museum.
In 2011, a gunman opened fire at a congressional meet-and-greet in Tucson, killing six people and wounding 13, including Giffords.
The former congresswoman's appearance came three weeks after two bombs killed three people and wounded more than 260 near the finish line of the Boston Marathon.
Before Sunday's ceremony, Giffords and her husband, retired astronaut and Navy Capt. Mark Kelly, visited victims of the bombings at a rehabilitation center, the Los Angeles Times reported.
Giffords and Kelly established Americans for Responsible Solutions, a political action committee that campaigns for, among other things, universal background checks on gun purchases.
Kennedy, daughter of President John F. Kennedy, praised Giffords during the presentation, saying the Kennedy family "is still suffering from the heartbreak of gun violence" and that Giffords "has turned a personal nightmare into a movement for change."
"When others would have withdrawn from public life, she's challenged us all to re-engage in the political process," Kennedy said.
John F. Kennedy was assassinated in 1963, and his brother, Robert, was assassinated in 1968, just after he'd won the California Democratic presidential primary.