The brutal attack happened at a property in Moneycannon Road area of Ballymoney.
Inspector Vince Redmond said: “We received a report that an 18 year old man had been shot four times, once in each arm and leg, at around 3.30am this morning by unknown intruders.
The injured man has since been taken to hospital for treatment to his injuries.“
It is understood his injuries are not life threatening.
“Our enquiries are at a very early stage into what was a brutal attack on a young man in his home by dangerous and violent individuals.
“I would ask anyone with any information which could assist us to apprehend those responsible to contact detectives at Coleraine on 101 quoting reference number 324 23/09/18.
“Alternatively, information can also be provide to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”