Kelley's career in entertainment began when he wrote and directed a short film entitled The Yellow Badge of Courage in 1999. In 2001 he served as a producer and writer on a television special entitled Earthship.TV, a display of footage from filmmaker James Cameron's expedition to the wreck of the R.M.S. Titanic. From 2003-2007 he served as a writer and producer on the CBS crime series NCIS, writing or co-writing sixteen episodes during this time. In 2010 he wrote a freelance episode of House, which aired as part of its sixth season. He was brought aboard as a staff writer at the beginning of season seven.