Bryant denied the charge hours later, fighting back tears at a news conference in Los Angeles and saying he was guilty only of adultery.
"I didn't force her to do anything against her will. I'm innocent," he said, sitting next to his wife, Vanessa. "I sit here in front of you guys furious at myself, disgusted at myself for making a mistake of adultery."
Bryant also said "I love my wife with all my heart." He then turned to her, saying "you're a blessing." He says they will fight the charges against him "shoulder to shoulder."
Bryant's attorney, Pamela Mackey, said Bryant will plead innocent and his defense will be that the sexual encounter was "between two consenting adults."
"Kobe Bryant is innocent of the charges that were filed against him today. He stands falsely accused," Mackey said.
"Kobe Bryant did not assault his accuser," she said.
The defense attorney said Bryant's actions since the allegation showed his innocence because he has cooperated with all requests of the sheriff's and district attorney's offices.
"No prosecutor should file charges unless the evidence is so strong that the case can be proved beyond a reasonable doubt," she said. "The evidence in this case falls far, far short of that standing. The accusations in this case cannot be proven because they are false."
The attorney said it was Bryant's decision to appear at the press conference.
Eagle County District Attorney Mark Hurlbert had announced the charges in an earlier press conference in Colorado.
"It is alleged that he had sexual penetration of intrusion and caused the submission of the victim through actual physical force," said Hurlbert.
Hurlbert told reporters the 24-year-old Bryant faces probation to life in prison if convicted on the single felony count.
"I feel that after reviewing evidence I can prove this case beyond a reasonable doubt," Hurlbert said.
The woman is well-known in Eagle as a former high school cheerleader and talented musician who auditioned for "American Idol" last year.
She worked the front desk at the exclusive spa where Bryant was staying while in Colorado for knee surgery. Hurlbert said she would not be made available for comment.
The Los Angeles Lakers guard insisted he was innocent.
"Nothing that happened June 30th was against the will of the woman who now falsely accuses me," Bryant said in a statement.
His wife, Vanessa, also released a statement, saying she stood by her husband. "He is not a criminal," she said.
Hurlbert refused to talk about the details of the case. He said he reviewed all evidence during the last two weeks and consulted prosecutors around the state before making his decision.
Bryant, free on $25,000 bail, must return to court in Eagle on Aug. 6 for a hearing.
The case has riveted the sports world for nearly two weeks because it involves one of the NBA's brightest and most magnetic young stars. The recently married father of a baby girl has also used his wholesome image to land multimillion-dollar endorsement deals.
Documents in the case, including the arrest warrant, have been sealed.
Authorities have said Bryant assaulted the woman June 30 at the gated Lodge & Spa at Cordillera in nearby Edwards. He was in Colorado for knee surgery at a Vail clinic, and was booked at the lodge from June 30 to July 2.
Eagle County sheriff's deputies took Bryant to Valley View Hospital in Glenwood Springs for tests early July 2, later letting him leave in a taxi with his bodyguards.
The woman also underwent tests, and Hurlbert has said he needed information from the state crime lab before making his decision.
Bryant surrendered to authorities July 4 and was released an hour later after posting $25,000 bond. The sheriff refused to release Bryant's booking photo for days.
The arrest was announced July 6, prompting a firestorm of media attention on this small mountain town 100 miles west of Denver. Reporters swamped the cul-de-sac where the woman lives with her parents, but she has said nothing publicly. Her family has consulted an attorney.
The news stunned basketball fans: Bryant, a five-time All-Star who already has won three titles with the Lakers, is by most accounts a quiet man who prefers dinner with a few friends to joining teammates for a night on the town.
Kareem Rush, an LA Lakers teammate of Bryant's, defended the star. Rush told CBS News Correspondent Bill Whitaker, "Knowing him as a teammate and knowing him and his character, it's totally ludicrous.
"Oh, no," said Patricia Brewer, who heard the news at LA's Staples Center, where her daughter was to play in a basketball game later in the day. "I love him so much and I'll still keep an open mind and hope that this is all a mistake.
"But you know, if it's true, then he's just another man masquerading as a family man, fooling us all, and that just makes your heart sink."
Brewer was among fans saying Bryant's image would suffer in their eyes whether he committed rape or adultery, but others, such as 16-year-old Robert Watts of Lancaster, said they didn't think admitting an affair would hurt the star.
"I look at him completely the same way. I think all men do it sometime or later. I don't know why," said Watts, wearing Lakers gold and purple outside the arena. He added that he didn't think Bryant had committed rape: "I think he just got in a bad situation."
Sports marketing experts say the case will be a permanent blow to Bryant's image, and could cost him millions in endorsements.
CBS' Whitakerspoke to sports marketing consultant David Carter about the effects of the charges on Bryant's high-profile endorsements.
If convicted, Carter said, "Something like this would be so off the charts for somebody of such high esteem that it would all but be over for him with all of his major companies."
Just last month, he signed a multimillion-dollar sneaker deal with Nike to go with contracts he already had with Sprite, McDonald's and Spalding.
Athletic-shoe giant Nike Inc. issued a statement declining to comment on his legal problems but saying, "As we have said before, we are pleased to have a relationship with Kobe Bryant. He is a great player."
The case also raises questions about Bryant's summer plans and whether he will be able to play with the U.S. Olympic qualifying team, which begins practice Aug. 10 in New York.
The Lakers begin practice in October for the 2003-04 season.
"Naturally, we're disappointed with today's announcement," Lakers general manager Mitch Kupchak said. "While there are many questions concerning this issue, we will wait for time and the judicial process to answer them."
NBA commissioner David Stern said the league would have no comment until the case is settled.
Bryant's image could help him in court, Loyola University Law School professor Laurie Levenson said.
"It comes down to the facts," she said. "It's tough enough in an average rape case to prove there was lack of consent and force. In this case it will be particularly difficult because people don't want to believe it."
Former NBA star Charles Barkley expressed support for Bryant, saying, "He has always been a great kid. I don't find this in his character.
"We don't know if the charges are true. That's the thing," Barkley said after completing play in a celebrity golf tournament at Lake Tahoe, Nev. "I don't look at him as a bad guy or whatever."
Bryant entered the NBA in 1996 at age 18, straight out of high school. He has drawn comparisons to the league's all-time greatest players as he helped Los Angeles win consecutive titles from 2000-02.
Along with his determination, Bryant also has shown qualities many fans feel are missing from other NBA stars. He wept when the Lakers were eliminated from the playoffs by San Antonio in May, and he wore his hospital ID bracelet in a game the day after his daughter was born.
He married Vanessa Laine in April 2001. The two met on the set of a music video where Laine was working and got engaged while she was still in high school. Vanessa Bryant gave birth to their first child, Natalia Diamante Bryant, in January.