Singh, known as the "guru of bling" on account of his flashy dress sense and penchant for diamonds, was convicted of raping two women in a case that dates back to 1999.
He is the spiritual leader of Dera Sacha Sauda, a controversial spiritual sect founded in 1948. The group describes itself as a "selfless socio-spiritual organization" and claims millions of followers worldwide.
After news of the verdict filtered out, supporters went on a rampage in towns across the northern Indian states of Punjab and Haryana, Reuters reported. Television vans were attacked, cars set on fire and hospitals struggled to cope with scores of injured.
In New Delhi, Singh's supporters set fire to buses and two empty train carriages.
Modi calls violence 'deeply distressing'
Prime Minister Narenda Modi appealed for calm. "The instances of violence today are deeply distressing. I strongly condemn the violence & urge everyone to maintain peace," Modi said on Twitter.
Gauri Prashar Joshi, the deputy commissioner in Panchkula, told CNN that at least 17 people had died in the chaos.
"There have been a lot of people injured and slowly family members are trickling in, and I've also requested the district Red Cross Society to send in their trained volunteers," Joshi said.
The official said 120 people had been admitted to the hospital and the army was called in to quell the violence, which had since subsided.
Cities in the north of India had braced for violence in the wake of the verdict as tens of thousands of Singh's supporters amassed in Panchkula, where the case was heard. They reacted angrily to news of the guilty verdict.
Rape in India carries a minimum sentence of seven years. Singh, who is also at the center of an ongoing murder investigation
, will be sentenced Monday.
The Dera Sacha Sauda sect has ashrams
scattered across 10 states and union territories in India and claims to have 60 million followers worldwide.
Singh wields considerable influence in India, where he is considered something of a cult cultural icon and performer. He is the star of five films and numerous popular music videos, including the "Messenger of God," in which he acts as the hero who saves the nation.
His look is part-biker gang member, part Hindu epic hero. In one of his most popular music videos, "Love Charger," Singh appears clad in a rhinestone-studded motorcycle vest with an embossed image of a lion on the back, while he sings before an adoring crowd.
India's Central Bureau of Investigation first picked up the case against Singh in 2002, but charges were only formally brought against him in 2007, according to the bureau's R.K. Gaur.