Ron Barber is a high-ranking staffer for Congresswoman Gabrielle Giffords.
The 65-year-old spent the past six months undergoing extensive physical therapy after being shot in the face and leg.
Barber, who now walks with a cane, will work part-time at Giffords' district office.
He says he still has vivid nightmares of the Jan. 8 shooting that killed six people and injured 13, including Barber and Giffords.
The shooting killed his colleague, Gabe Zimmerman, and John Roll, Barber's college buddy and a federal judge.
Another Giffords' staffer, Pam Simon, was wounded in the shooting after taking a bullet to the chest and one to the wrist. She returned to work in February.
Jared Lee Loughner, 22, has pleaded not guilty to charges stemming from the shooting. He is being held at a Springfield, Mo., facility undergoing treatment that is meant to make him mentally competent to stand trial.
The Associated Press contributed to this story