The arrest was made on the same street where the off-campus party was being held when Moore was shot. The 19-year-old student died the next day from her injuries.
"He's definitely the shooter," a law-enforcement source said of the suspect who was taken away within minutes after police raided the house.
Sources tell NBCNewYork that suspect, identified at Nicholas Welch, 25, will be charged with four counts of attempted murder and one count of murder. Arraignment will likely be Wednesday in Newark.
Welch, 25, of East Orange lives just doors from where the party was taking place, authorities said. Another man, Marcus Bascus, 19 is being sought for providing the weapon.
Both men are charged with murder. Welch is being held on $2 million bail, said Essex County Prosecutor Robert Laurino at a press conference late Monday night.
As police and several people who were at the party described, the shooter had allegedly tried to crash a party just after midnight Saturday but was hustled out the door.
That allegedly prompted him to go his buddy on the sidewalk and say, "Give me the banger."
Then, police say, he went back inside of the party and opened fire. In addition to Moore, four others were hit by gunfire, though none critical.
Two of the injured are 19-year-old women who go to Seton Hall, and one is a 25-year-old man who attends the New Jersey Institute of Technology. The other is a 20-year-old man from New York who is not a student.
Lawmen say they expect to arrest another person being questioned as well.