Giunta has opted not to re-enlist and will leave the Army in mid-June, said Army spokesman George Wright. Giunta and his wife, Jenny, plan to move to Fort Collins, Colo., where he will attend school.
Wright said he didn't know what school Giunta will attend, but Fort Collins is home to Colorado State University.
Giunta, 26, is the first living service member from the wars in Afghanistan or Iraq to receive the Medal of Honor, the nation's highest military honor.
His decision not to re-enlist was made before Giunta received the medal, his public affairs officer Todd Oliver wrote in an e-mail on Tuesday from Italy.
"Giunta and his wife decided on leaving the U.S. Army a few years ago," Oliver said. "They both feel that this is a good time to separate from the service so that he can continue his education."
A decision on which school Giunta would attend was "still up in the air," Oliver said.
He said Giunta was not available for comment on Tuesday and was flying back to Italy on Wednesday. Giunta is with the 2nd Battalion, 503rd Parachute Infantry Regiment, 173rd Airborne Brigade and is assigned to a base in Vicenza, Italy.
Giunta was serving as a rifle team leader in Afghanistan when his platoon was attacked in 2007.
In announcing the award, the White House noted he went beyond the call of duty by exposing himself to enemy fire to pull a soldier back to cover. He also shot two insurgents who were trying to carry away a U.S. soldier.
Giunta has since been the Army's most noted serviceman, waving to the crowd from the field at the Super Bowl and appearing on late-night television shows. He sat with first lady Michelle Obama for President Barack Obama's State of the Union address last month.
Col. Greg Hapgood, a spokesman for the Iowa Army National Guard, said Giunta is an "incredibly high-quality young man and wonderful ambassador for the Army and the United States."
Hapgood called it "a huge loss to the military" to have him leave the Army, but said he is happy for Giunta because whatever his dream is, "he will pursue it."
Giunta enlisted in the Army in November 2003 after graduating from Kennedy High School in Cedar Rapids. He was in his second tour of duty in Afghanistan at the time of the ambush. In an earlier interview with The Associated Press, he refused to take credit for any extraordinary feats.
"I did my job and I did it to the best of my ability," he said.
Giunta's family did not immediately respond to a telephone message Tuesday.
His father, Steven Giunta, told the AP in an earlier interview that his son was humbled because he believes he was just doing what he was supposed to be doing.
"He mentions every other soldier would have done the same thing. It kind of rocks his world that he's being awarded the Medal of Honor for something each and every one of them would have done. He's very aware of that," he said.
One of Giunta's high school teachers, Michelle Frye, said she was "thrilled" he was getting out of the Army and was continuing his education.
"He loves to learn," she said. "This is really good for him. I think he will appreciate school, whatever it is he does, so much."