A 17-year-old boy was found with stab wounds in a house on McDougall Street, Casino, by emergency services, who were called at 1.20am on Saturday morning.
He was attended to by police and paramedics, but could not be rescued.
Police believed the attack was a target.
The 18-year-old was charged after being arrested at a local home.
The man was denied bail to appear in Lismore local court on Monday.
The crime scene has been set up in the house and is being forensically examined, police said.