Steven Chase set up the Playpen site on the Tor dark web network in early 2014.
By the time it was shut down a year later it had more than 150,000 users and hosted more than 50,000 images and videos.
The FBI said the removal of Playpen had led to almost 300 abused children being identified or rescued.
Chase was tracked down after accidentally disclosing the IP address of the server hosting the Playpen site. The way Tor works meant routine ways of locating a computer did not work.
Chase's mistake was spotted by a foreign police force and the information was passed to the FBI because the server was in the US.
In February 2015, the FBI raided the North Carolina firm hosting the Playpen server and took control of the computer. The raid led the agency to track down Chase and Playpen staff.
Two other men who helped Chase run Playpen have already been given jail terms. Each one received a 20-year sentence.
The FBI kept the Playpen site running for two weeks after taking control of it and used malware to monitor and locate its users.
As a result, it said, more than 800 people around the world have been arrested for their part in either abusing children or distributing sexual abuse material.
"Members of his enterprise who were raping children, who were producing child pornography all around the world - those cases continue to be indicted and prosecuted," said special agent Dan Alfin from the FBI's Violent Crimes Against Children unit who helped co-ordinate the investigation.