Jason 'Jace' Alexander, 51, allegedly published a short film on the file-sharing site Torrent showing a 12-year-old girl performing sex acts in June, according to a police report seen by the New York Post.
The married father-of-two was investigated after detectives found child pornography online and traced the IP address to his home in Westchester County, New York, the report claims.
Charged: Jace Alexander (pictured left in his police mugshot, and right at Trump National Golf Club in 2013) has been charged with child sex abuse for allegedly posting a video online of a young girl masturbating
During his 21-year career, Alexander has directed numerous episodes of Law & Order (pictured on set, above).
During a search on the property, police allegedly found another video on Alexander's computer that shows a six-year-old girl masturbating.
He was arrested on Wednesday afternoon and posted $10,000 bail. He will appear at Dobbs Ferry Court in Westchester County, New York, on November 19.
If convicted, Alexander faces up to seven years in state prison.
Alexander, who has also directed TV shows such as Rescue Me and The Blacklist, is the only child of Emmy-award-winning actress Jane Alexander.
His stepfather is director-producer Edwin Sherin, who has also directed episodes of Law & Order.
Lengthy career: Married father-of-two Alexander, 51, has been working as a director in the TV business for 21 years.
Family: His wife is actress Maddie Corman (left) and his mother is two-time Emmy winner Jane Alexander (right).
Maddie Corman, has starred in Law & Order and Maid In Manhattan. The couple have two 11-year-old twin sons.
Alexander's 21-year career includes a TV movie about Jodi Arias, the aspiring photographer who was found guilty of murdering her lover in a murder trial that gripped the nation.
He has also worked as an actor. He starred in Eight Men Out with John Cusack and Charlie Sheen. In 1988 he appeared in Crocodile Dundee II as a hobo, and in 1994 he played the part of a robber in the hit show Clueless.