The sentence was handed down in federal court in Alexandria, Virginia, the U.S. Justice Department said and includes a three years' probation after his prison term.
Morton pleaded guilty in February to making threatening communications, using the Internet to put others in fear and using his position as leader of the Revolution Muslim organization's Internet sites to conspire to commit murder.
Help: The website, pictured, led to the arrest of a second conspirator Zachary Chesser, who also pleaded guilty to sending threatening messages to the show's writers
He had worked on website postings with Zachary Chesser of Virginia, who pleaded guilty in October of 2010 to sending threatening communications to the 'South Park' writers and to other charges.
Morton was arrested in Rabat, Morocco, last year and brought back to the United States, where he pleaded guilty. He had faced a maximum sentence of 15 years in prison.
Morton admitted he helped Chesser in taking repeated steps in April of 2010 to encourage violent extremists to attack the 'South Park' writers for the episode on the cable channel Comedy Central that featured the bear suit.
Always controversial: South Park character Eric Cartman is seen in one episode with former Al Qaeda leader Osama bin Laden
'Is that OK to show?' a character in the South Park episode hesitantly reacts to a stick figure representing the prophet on a sheet of paper.
'I don't know. I guess we'll see,' a second responds.
Most Muslims consider any depiction of the founder of Islam as offensive.
Morton and Chesser posted where the writers resided and encouraged online readers to 'pay them a visit,' according to court documents.
Morton worked with Chesser to draft a message for the website about the South Park threats and they posted a final version of the statement on various extremist online forums.
Outrage: Most Muslims consider any depiction of the founder of Islam as offensive, enraging Morton by his drawn image in a bear suit
Morton also conspired with Chesser and others to solicit the murder of an artist tied to the 'Everyone Draw Mohammad Day' movement in May 2010, including posting online a magazine that included the artist in a hit list for violent extremists.
Chesser was sentenced to 25 years in prison last year.
The case is USA v. Morton, No. 12-cr-35, in U.S. District Court for the Eastern District of Virginia.