Jason Lawrance, 50, of Britain, used the site to contact women online and then met them in person.
He persuaded them to give him their contact information by claiming he could not upload a photo to his online profile. After meeting them, he raped, tried to rape or assaulted them.
Lawrance, of Liphook, a village 50 miles southwest of London, was convicted Wednesday of five counts of rape, one of attempted rape and one of sexual assault. He denied the charges.
A statement by the Crown Prosecution Service said Lawrance raped his first victim in a van on a dark country lane in 2011. After having met her a few times, he tricked her into getting into the vehicle with him.
He later sexually assaulted a woman in her car, and attacked other women in hotel rooms or their own homes.
His attacks were only stopped when one of his victims reported the assault to the police.
When police looked into his dating activity, they found evidence of attacks on six other women, the statement said.
"Jason Lawrance is a dangerous sexual predator. He has gone from victim to victim, targeting them through online dating sites," Sue Matthews, senior crown prosecutor at the CPS East Midlands rape and serious sexual offenses team, said in a statement.
"Nobody should feel that meeting people through a dating site means that they are consenting to any sexual activity.
"If a person does not consent to sexual activity and the perpetrator does not reasonably believe they are consenting, that is an offense, regardless of how the victim meets the perpetrator, or how well they know each other."
'He may never be released'
A jury unanimously found Lawrance guilty of all charges after a two-and-a-half week trial at Derby Crown Court.
His 12½ year minimum sentence will be reduced by the 425 days he has already served.
"The length of the sentence today reflects the severity of his crimes and I am pleased that we have been able to achieve justice for the victims," said Detective Chief Inspector Allison Rigby, who led the police investigation.
"The life sentence he has been given means that he may never be released," Rigby said.
It is important to remember, she said, that seven women were abused by Lawrance -- and they had to relive their ordeals in court in front of strangers.