Giffords wore glasses and her hair remains short. But she stood and acknowledged the loud applause and cheers of her House colleagues, waving to them as a crowd formed around her.
During her visit, Giffords also cast a vote, in favor of the debt agreement.
Her appearance seemed to catch many House members by surprise; as the vote continued, a note on her Twitter account — which until Monday night had been silent since July 29 — read, "The Capitol looks beautiful and I am honored to be at work tonight." That followed a brief tweet announcing her intention to support the debt bill.
Giffords' office released a statement after the vote was over. In it, she said, "I have closely followed the debate over our debt ceiling and have been deeply disappointed at what's going on in Washington."
"After weeks of failed debate in Washington, I was pleased to see a solution to this crisis emerge. I strongly believe that crossing the aisle for the good of the American people is more important than party politics. I had to be here for this vote. I could not take the chance that my absence could crash our economy."
Her office also noted that Giffords had previously stood against increases to the U.S. debt limit, in 2009 and 2010. The debt ceiling bill now moves to the Senate, which is expected to hold a vote sometime around noon Tuesday.
Giffords was shot on Jan. 8 in Tuscon. She was holding a meet-and-greet event at a strip mall. Six people were killed and 13, including the congresswoman, were wounded.