Aydin C, 38, was found guilty of internet fraud and blackmail on Thursday in Amsterdam.
He faces additional cyberbullying charges in Canada in connection with the online harassment of Amanda Todd.
The 15-year-old Todd killed herself in 2012 after photos of her breasts were published online.
The man, who is identified only by his first name because of Dutch privacy rules, was arrested in January 2014.
He was accused of harassing 34 young women and five gay men, from countries as far away as Britain, Canada, Norway and the United States.
He pleaded not guilty to 72 charges, including making and storing child pornography, extortion, fraud and the possession of hard drugs.
He "abused dozens of young girls by gaining their trust through speaking with them on the internet," the court said.
"He then abused that trust by forcing them to perform sexual acts before their webcams. If they refused to do it again, he threatened to send their images to their relatives or to publish them on pornography sites."
Some of the victims were harassed for years, the court heard.
In June 2016, a Dutch court approved his extradition to Canada, where he faces charges in British Columbia related to making and distributing child pornography, extortion and harassment. That ruling is under appeal before the Dutch Supreme Court.
In October 2012, Todd killed herself just five weeks after posting a harrowing video detailing the bullying she suffered after photos of her breasts were published online. The YouTube video was viewed millions of times, and sparked a global discussion about online harassment.
In the video, Todd said she was lured by a stranger to show her breasts on a webcam. Those photos were then published on a Facebook page and sent to people in her community. She said she had to change schools multiple times because of bullying.
Todd's mother attended the Netherlands trial and told media she was "relieved" about his sentence.
"I hope that this sentence will help the wounds of all the victims heal. It has been a long journey for all of us in the search for justice for Amanda," Carol Todd told AFP.
A Dutch man was sentenced to 11 years for blackmailing dozens of young women around the world into performing sex acts in front of web cams.