The 15-year-old victim is in the hospital in serious but stable condition.
Nassau County police say Floyd McNeil Jr. of Hempstead was arrested Tuesday night.
He was charged as an adult with attempted murder, assault and possession of a dangerous weapon.
He was ordered held on $150,000 bail at his arraignment Wednesday. He was represented by an attorney from Legal Aid, which does not comment on pending cases.
Police say the stabbing occurred around 3 p.m. Monday in a parking lot in Hempstead. They say the victim was surrounded by a large group of people, one of whom stabbed him in the abdomen.
The motive was not immediately known.