Conrad Alvin Barrett, 27, of Katy, Texas, has been charged with one count of violating the Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act.
According to the federal complaint, Barrett attacked the elderly man "because of the man's race and color."
The suspect made a video of the attack November 24, the complaint said. In the video, he allegedly commented that "the plan is to see if I were to hit a black person, would this be nationally televised?"
He then allegedly "hit the man with such force that the man immediately fell to the ground. Barrett then laughed and said 'knockout,' as he ran to his vehicle and fled."
The victim suffered two jaw fractures and was hospitalized for several days, the complaint said.
Barrett's attorney, George Parnham, told CNN his client remains in jail. His client has bipolar disorder and takes medication, Parnham said.
Parnham said he could not state whether his client carried out the attack, but, "mental health issues definitely played a part in anything that occurred."
Barrett "is very sorry for this person," Parnham said, adding that he and his client haven't had much opportunity to discuss the facts of the case.
The "knockout game" is an assault in which an assailant aims to knock out an unsuspecting victim with one punch.
According to the Justice Department complaint, there have been "knockout game" incidents, some of which have been called other names, as long ago as 1992.
New York police previously charged suspect Marajh Amrit with a hate crime in the alleged attack of a white Jewish man as part of a "knockout" game.
Similar cases have been reported recently in several states, including Illinois, Missouri, and Washington.
"Hate crimes tear at the fabric of entire communities," U.S. Acting Assistant Attorney General Jocelyn Samuels said Thursday in a Justice Department statement announcing the charge against Barrett. "As always, the Civil Rights Division will work with our federal and state law enforcement partners to ensure that hate crimes are identified and prosecuted, and that justice is done."
Barrett, who is white, allegedly recorded himself on his cell phone attacking the man and showed the video to others. the department said. "The complaint alleges Barrett made several videos, one in which he identifies himself and another in which he makes a racial slur. In addition, Barrett had allegedly been working up the 'courage' to play the 'knockout game' for approximately a week."
The victim's face was swollen on one side, and he has had to suck out of a straw in order to drink, a nephew, Joseph Lewis, told CNN affiliate KTRK-TV in Houston.
Barrett allegedly told an off-duty police officer what happened and even shared a video, saying he felt bad, the TV station reported.
In other videos on his phone that police confiscated, Barrett used the N-word and said that African-Americans "haven't fully experienced the blessing of evolution," according to the criminal complaint.
"It is unimaginable in this day and age that one could be drawn to violently attack another based on the color of their skin," said Special Agent in Charge Stephen Morris of the FBI's Houston office. "We remind all citizens that we are protected under the law from such racially motivated attacks, and encourage everyone to report such crimes to the FBI."
In a separate case, New York City police on Wednesday searched for a man who allegedly punched a 33-year-old woman in the back of the head in Brooklyn in what may be a "knockout" assault.
Despite that and other cases, New York Police Commissioner Ray Kelly said last month city officials haven't yet seen evidence of a trend, though they are not ruling out the idea.
"The press has named it the so-called knockout game. We don't discount that that exists. It's a possibility. We've investigated and will continue to investigate," Kelly told reporters in late November.