NYC knife law is covered under the New York City Administrative Code § 10-133.
b. It shall be unlawful for any person to carry on his or her person or have in such person's possession, in any public place, street, or park any knife which has a blade length of four inches or more.
c. It shall be unlawful for any person in a public place, street or park, to wear outside of his or her clothing or carry in open view any knife with an exposed or unexposed blade unless such person is actually using such knife for a lawful purpose as set forth in subdivision d of this section.
d. The provisions of subdivisions b and c of this section shall not apply to
(1) persons in the military service of the state of New York when duly authorized to carry or display knives pursuant to regulations issued by the chief of staff to the governor;
(2) police officers and peace officers as defined in the criminal procedure law;
(3) participants in special events when authorized by the police commissioner;
(4) persons in the military or other service of the United States, in pursuit of official duty authorized by federal law;
(5) emergency medical technicians or voluntary or paid ambulance drivers while engaged in the performance of their duties; or
(6) any person displaying or in possession of a knife otherwise in violation of this section when such knife
(a) is being used for or transported immediately to or from a place where it is used for hunting, fishing, camping, hiking, picnicking or any employment, trade or occupation customarily requiring the use of such knife; or
(b) is displayed or carried by a member of a theatrical group, drill team, military or para-military unit or veterans organization, to, from, or during a meeting, parade or other performance or practice for such event, which customarily requires the carrying of such knife; or
(c) is being transported directly to or from a place of purchase, sharpening or repair, packaged in such a manner as not to allow easy access to such knife while it is transported; or
(d) is displayed or carried by a duly enrolled member of the Boy or Girl Scouts of America or a similar organization or society and such display or possession is necessary to participate in the activities of such organization or society.
