The decision Friday by the Ohio High School Athletic Association comes four days after James, a senior at St. Vincent-St. Mary, was cleared after receiving a $50,000 sport utility vehicle from his mother.
Last Saturday, James was given two retro sports jerseys from a clothing store. The jerseys, honoring former Chicago Bears running back Gale Sayers and former Washington Bullets center Wes Unseld, cost a combined $845.
James' school, St. Vincent-St. Mary, must forfeit Sunday's game, the association said. The school, ranked No. 1 by USA Today, has five games left in the season, in addition to playoffs.
The 6-foot-8 James is considered the best high school player in the country and is expected to be the top player selected in June's NBA draft.
Ohio high school officials reviewed a report that James received two free "throwback" jerseys worth $845 at a clothing store in Cleveland.
The association said James received clothing in exchange for posing for pictures to be hung on the store's walls.
The association's rules say an athlete forfeits amateur status by "capitalizing on athletic fame by receiving money or gifts of monetary value."
"In talking with the store's personnel, I was able to confirm that on Jan. 25 the merchant gave clothing directly to LeBron at no cost," said OHSAA Commissioner Clair Muscaro. "This is a direct violation of the OHSAA bylaws on amateurism, because, in fact, LeBron did capitalize on athletic fame by receiving these gifts."
St. Vincent-St. Mary has five games left in the season, in addition to playoffs.
James refused to comment about the jerseys Thursday night at the Greater Cleveland Sports Awards. However, he did allude to "all the controversy that's going on with me" during his acceptance speech after being named the area's top high school athlete for the second straight year.
"I'd like to thank my teammates for helping me through all this," he said. "It will be in the paper, but remember I'm on the honor roll with a 3.5 grade-point average."
On Monday, Muscaro ruled that James would not lose his eligibility for accepting a custom-made Hummer H2 vehicle valued at about $50,000 as an 18th birthday gift from his mother.
At the time, Muscaro said no violations of the OHSAA amateur bylaws "as currently written" have been found and that James is still eligible to play.
Gloria James had provided loan information to support her purchase.
"In working with the attorney for the James family and the OHSAA attorney, I was shown official business records from the bank and the dealership which established that the financing and acquisition of the vehicle were procured by the student-athlete's mother alone," Muscaro had said in a statement. "Accordingly, this type of transaction is not a violation of the OHSAA bylaws on amateurism."
Muscaro said he asked school administrators at St. Vincent-St. Mary on Friday for a chance to speak with James.
"But LeBron did not want to speak with me," said Muscaro, who added he had never ruled an athlete ineligible before in his 14 years as commissioner.
"I think this sends a message that we are all about fairness," Muscaro said. "LeBron is being treated like anyone of the thousands of student athletes in Ohio."
Muscaro said his ruling was not an accumulation of evidence, and it was specific to James receiving the two jerseys.
"Naturally, LeBron is talented and he's noted nationally and internationally, but as far as this association is concerned, we will treat him the same as all our other athletes."