Mr. Bush called them "men who knew the cost of freedom and were willing to pay that cost so others could live free."
During a visit to the Walter Reed Army Medical Center, the president urged Congress to break the current stalemate and pass legislation that "must be comprehensive."
The three injured soldiers who took the oath and became citizens were Spc. Noe Santos-Dilone of Brooklyn, N.Y.; Spc. Sergio Lopez of Bowlingbrook, Ill.; and Pfc. Eduardo Leal-Cardenas of Los Angeles.
Santos, who stood on crutches while the other two were standing on their own at the ceremony, was injured last Sept. 6 when the convoy in which he was riding was bombed. Lopez was injured when his Humvee was hit by a roadside bomb south of Baghdad last Jan. 6. Leal-Cardenas was injured by a roadside bomb last Dec. 6 while returning to his base from a mission just south of Baghdad.
Mr. Bush called it, "a joyful day for these men, a joyful day for me to be here with them...It's a privilege to be their commander in chief."
"This isn't going to be the first time these men have made such a promise. They took a similar oath when they became soldiers of the United States Army. And their presence here bears witness that they kept their word so that others might be free," Mr. Bush said.
"As our nation debates the future of our immigration policies, we must remember the contribution of these good men and all who dream of contributing to this country's future," he said.
After the Sept. 11, 2001, terror attacks, Mr. Bush signed an executive order making foreign-born members of the U.S. military immediately eligible for U.S. citizenship when they serve on active duty.
"It made sense to me: If somebody's willing to risk their lives for our country, they ought to be full participants in our country," Mr. Bush said. He noted that more than 33,000 non-U.S. citizens currently serve in the military.
Trying to break the deadlock on immigration legislation, Mr. Bush said securing the nation's borders must be the first goal. After that, he said, it must offer a temporary worker program, tougher penalties for employers who hire undocumented workers, resolve the status of the million of illegal workers now in the country while honoring "the great American tradition of the melting pot."
The Senate earlier in the year passed a bipartisan immigration bill offering a chance at citizenship for millions of illegal immigrants and generally delivering on the goals outlined by Mr. Bush.
But the House, which in 2005 passed a far-more-restrictive bill that would make it a felony to enter the United States illegally, is holding a series of time-consuming hearings on the subject, hearings that have been criticized as a political maneuver to delay the legislation and help Republican candidates in an election year.