In her first public comments since the massacre at her meet-the-voters event in Tucson, Arizona, in January, Miss Giffords confirmed to colleagues and supporters: "I will get stronger - I will return."
It emerged in a leaked copy of a new memoir written with her husband, Commander Mark Kelly. Miss Giffords, 41, reads the final chapter - titled Gabby's Voice - for the audio book edition.
The book discloses that her first recollection of the incident after she regained speech was "Shot. Shocked. Scary". She then redeveloped her ability to talk by reciting the U.S. constitution and Martin Luther King Jr's "I Have a Dream" speech.
Readers also learn Miss Giffords was trying to have a baby and had several rounds of fertility treatment before being shot by Jared Lee Loughner, the 23 year-old dropout being prosecuted for killing six people and wounding 13. She has also lost half the sight in both eyes, it states.
The new details came as footage was released of Miss Giffords laughing and chatting with Mr Kelly on a sofa at their house in Texas for an interview due to be broadcast the evening before the book's release later this month. It heralds her return to the public eye, 10 months after her bloody body was carried from a supermarket car park on a stretcher and her death was reported by National Public Radio.
It remains unclear if Miss Giffords - who is nationally adored at a time when public approval of Congress is at an all-time low - will run for re-election next November or try to return at a later date.
She walks with a cane, has become left-handed, and will only complete the latest phase on Saturday of her "intensive therapy" at a specialist centre in North Carolina.
But with evident determination, money in the bank, and a renown exceeding that of practically all her colleagues, she is widely expected to exploit any possibility to do so.
Debbie Wasserman-Schultz, a Florida congresswoman who is Miss Giffords's closest friend in the House of Representatives, has said every effort is being made to help her prepare.
"We're certainly getting her ready, to make sure she can run for re-election at the point that they're ready to decide," she told an interviewer. "Her supporters and he colleagues are making sure she doesn't have to run from scratch when she makes that decision."
Miss Giffords's presumed campaign has raised about $830,000 (pounds 518,000) for this election cycle and has already spent about $330,000 of this - almost double what she had spent at this point in 2009, when there was no question that she was running.
Other candidates bold enough to stand against her, depending on constituency boundary changes, have already encountered fierce local opposition.
Anthony Prowell, a special needs teacher, was attacked as a "vulture" and "low-life scum" after indicating that he would challenge Miss Giffords for the Democratic nomination.
"People say that she's had this horrific accident and you guys are like a bunch of sharks sniffing blood," Mr Prowell, who is now preparing to stand as a Green Party candidate, told The Daily Telegraph.
Frank Antenori, a Republican state senator and decorated Iraq War veteran who is preparing a run for his party's congressional candidacy, said he may be forced to scrap his plans if Miss Giffords runs.
"I'll be honest, it's got a lot to do with the fact that she's going to be tough to beat," he said. "If she's physically able to run, in all likelihood I won't be."