Raised as the youngest of seven children, he received acting gigs from an early age as his older brother Macaulay Culkin was starring in films as early as 1990. Rory's big screen debut came in the 1993 feature The Good Son, which starred Macaulay.
He played the character Craig Hansen in a 2002 episode of The Twilight Zone.
His brother Kieran has also had a successful acting career. Apart from Macaulay and Kieran, he has two other brothers, Christian and Shane, and a sister, Quinn. Another sister, Dakota, tragically died after being struck by a car in 2008.