In a statement, Giffords -- who has been recuperating since the operation and whose return came as a total surprise to most -- said that she felt the need to come back to work as default loomed.
"I had to be here for this vote," she said. "I could not take the chance that my absence could crash our economy."
Giffords voted against increasing the debt ceiling twice, in Dec. 2009 and Feb. 2010, but staff said in her statement that "this vote was substantially different, with the strength of the U.S. economy hanging in the balance."
Giffords stole the show well before the vote fell into the passing range. The House, which has been consumed for weeks on finding a way to raise the debt ceiling and avoiding sending the country into default, was mesmerized by her arrival with colleagues from both sides of the aisle lining up to hug her. Minority Leader Nancy Pelosi (D-CA) hugged her and wiped away a tear from her eye.
Rep. Jeff Flake (R-AZ), who could oppose her in a Senate campaign should she decide to run, made a beeline to the Democratic side of the aisle, and waited his turn for the chance to embrace her.
Vice President Joe Biden was also on hand to greet Giffords.
Giffords was severely wounded when a gunman attacked a constituent services event she was holding in her Tucson, AZ district back in January. Six people died in the attack, including a nine-year old girl, a federal judge and a member of Giffords' congressional staff. Giffords was in the hospital for months, finally being released in June.
Here's video of her returning to the House floor Monday:
Susan Crabtree contributed.