Houston Rockets player Kevin Porter Jr. was arrested on Monday ... after allegedly hitting his girlfriend and putting his hands around her neck.
Law enforcement sources tell TMZ Sports the incident happened at the Millennium Hotel in New York.
We're told police responded to a call of a dispute around 6:45 AM ... and at the scene, cops observed a laceration on the right side of the 26-year-old woman's face.
The woman -- who also complained of neck pain -- claimed KPJ struck her multiple times throughout her body during the physical altercation.