The incident took place at a student centre late on March 6.
Kemon Edwards is charged with discharging a firearm, carrying a concealed weapon, careless use of a firearm and other weapons offences, as well as aggravated assault and assault causing bodily harm.
Police said Friday a search at an address in the city's northwest prompted them to lay additional charges including possession of cocaine and heroin, and possession for trafficking purposes.
That search also led to the arrests of two men and two teen boys on charges police said are unrelated to the shooting.
Dominic Bernard, 20, Alex James, 23, and two boys aged 16 and 17 are facing drug and weapons charges.
The north Toronto university expressed relief at the arrest and said it would continue to co-operate with investigators.
The university said it had taken several measures to "enhance safety" on campus in the aftermath of the shooting, which included increasing security patrols.
Police have said they don't believe the two women who were shot at York University were targeted.
One woman was shot in the leg and was taken to hospital with serious but non-life threatening injuries.
A second woman was injured by shrapnel.
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