Giffords had some pain and nausea shortly after the surgery, but a scan of her brain showed the operation was successful, said Dr. Dong Kim, the neurosurgeon who performed the intricate, three-and-a-half-hour procedure.
She's doing so well that doctors are beginning bedside rehabilitation therapy, and say she's on the path to being released, although they won't discuss a timetable.
Giffords' head was shaved for the surgery, and she'll be able to stop wearing the cumbersome helmet that was protecting her head from further injury. Kim described her new look as "cute."
"I started calling her gorgeous Gabby today," Kim said at a hospital news conference Thursday. "She hasn't looked in the mirror yet, but as soon as she does she'll be very pleased."
Doctors had to remove a piece of the congresswoman's skull to allow for her brain to swell after she was shot in the head four months ago at a political meet-and-greet in Tucson, Ariz. Six people were killed in the attack and thirteen others injured, including Giffords.
To replace the missing bone, Kim attached a piece of molded hard plastic with tiny screws.
Giffords' astronaut husband, Mark Kelly, who is orbiting Earth on the space shuttle Endeavour, said he kept in touch with his mother-in-law, his identical twin brother Scott, and his wife's chief of staff throughout the surgery, and that he is pleased with how it went.
"She's doing really well. Everything went as planned," Kelly said in a TV interview from space. "Her neurosurgeons are very happy, she's recuperating and she's actually getting back to therapy today. So it went really, really well."
Kelly also said that Giffords will receive outpatient care in Houston, meaning she will remain away from her home district in Arizona for the start of the next phase of her recovery. "We don't know exactly when that is going to be, but I'm looking forward to that."
Giffords also had a permanent shunt placed in the skin behind her ear to drain spinal fluid from her brain and into her abdomen, Kim said. It will relieve pressure from fluids that often build up in patients with a brain injury, but it's not visible and many patients forget they have one, doctors said.
The surgery carries a 5 to 10 percent risk of infection, Kim said. There are still some remaining bullet fragments in Giffords' brain that will not be removed because doing so could make her condition worse, he said.
Once Giffords returns to TIRR Memorial Hermann in Houston from the nearby Memorial Hermann-Texas Medical Center where she underwent the surgery, the shunt and the skull surgery will further help her recovery.
"We're optimistic that when she comes back we'll see a lot of changes that will allow us to upgrade the rehabilitation," said Dr. Gerard Francisco, the head of Giffords' rehabilitation team.
Associated Press aerospace writer Marcia Dunn in Cape Canaveral, Fla., contributed to this report.