The HOME ALONE star says admits he used the drug recreationally, but insists he shouldn't be labelled a "drug user".
Culkin was arrested while he was driving through Oklahoma, where officials found marijuana and prescription anti-depressants in his car.
He says, "It's not something I make a habit out of, I had to talk to a counsellor.
"I had to pee in a cup to show them that, 'Listen, this is not a lifestyle for me, it's more out of character really.'"
The 25-year-old star claims the Oklahoma district attorney was prejudiced against him because of his fame.
He adds, "I think he had a lot of pre-conceived notions of who I was and just the whole child star, Hollywood kind of thing, of course we're all drug addicts, apparently."
Macaulay Culkin at his book launch entitled ' Junior ' held at Barnes and Noble in Union Square
New York City, USA - 13.03.06