The victim was taken to Blacktown Hospital by his friends and was later transferred to Westmead Hospital. He is in a stable condition.
Another 17-year-old boy was arrested at the scene after police spoke to partygoers.
He was taken to Castle Hill police station where he was charged with wounding with intent.
He was granted conditional bail and is due to appear in the Children’s Court on September 29.
Friends of the Box Hill stabbing victim have expressed their concerns online.
One friend who said he was at the party posted, “Was perfectly fine until this bullshit happened, to think I was talking to him face to face literally five minutes before this happened. Know you’ll pull through brother.”
The attack was the latest in a spate of stabbings in Sydney allegedly involving teenagers.
Last week, a 17-year-old boy was charged with stabbing a middle-aged man multiple times after an altercation at Kirawee station.
Aidan Smith, 16, died after being stabbed in a brawl at a house party in Ryde on Victoria Road last month. A 20-year-old man was charged with affray.
In July, a large fight outside a convenience store in Panania ended with Adam Abu-Mahmoud, 18, dying from stab wounds. Three people aged 20 and under were charged with murder.