During the fight, investigators said Joel Foster slashed George Pinckney by his right ear.
The altercation spilled onto the court before it was broken up by school security.
Pinckney, 44, drove himself to Southside Hospital in Bay Shore where he received 15 stitches to close the cut by his ear. He was later released.
Investigators located and arrested Foster, 21, on Wednesday afternoon.
Foster was charged with one count of second degree assault. He will be arraigned at First District Court in Central Islip, on Thursday.
The fight broke out with 1:03 left in the Class B championship, where Malverne defeated Wyandanch, 79-71.
The Wyandanch interim superintendent of schools, Dr. Pless Dickerson, told Eyewitness News that the brawl started when someone in the stands made disparaging remarks about one of the Wyandanch players as Wyandanch was on the verge of losing the game in the final minutes.
Fighting broke out when the father of the player heard the remarks and became incensed.
The fight apparently involved former students and the family of the Wyandanch team member. No one from the opposing team or its fans was involved. Dickerson insists that no current Wyandanch students were involved.
It started, he says, "when words were exchanged about a young man's playing ability."
"No father wants to hear that his son wasn't good at the sport he was playing," he said. "But that's no justification for what happened."
The investigation is continuing. Detectives are asking anyone with information to contact the Third Squad at 631-854-8352.