Spiritual leader Asaram was convicted of assaulting the woman several times between 2001 and 2006 at his spiritual retreat in the western state of Gujarat.
The ruling came as the 81-year-old is currently serving a similar life sentence, after being found guilty of raping another 16-year-old girl in 2018.
His lawyer said he would appeal against the court's latest ruling.
Asaram, known for his teachings on yoga and meditation, has millions of followers and hundreds of spiritual retreats around the world.
And tightened the authorities in the state of Gujarat security measures before the court's decision on Tuesday, due to fears of possible violence by supporters of the spiritual leader.
The day before, Asaram was found guilty by the court in Gandhinagar city under various sections of the Indian Penal Code, including on charges of rape and wrongful detention.
Six other defendants in the case, including Asaram's wife and daughter, were acquitted for lack of evidence.
Also on Tuesday, the court imposed a fine of 23,000 rupees ($281) on Asaram and ordered him to pay 50,000 rupees in compensation to the victim.
Allegations of sexual assault first surfaced in 2013 when the woman filed a complaint against the guru.
The woman alleged that Asaram raped her several times at his spiritual retreat in the city of Motira, where she was locked up for five years before she managed to escape.
In 2019, Asaram's son, Narayan Sai, was also sentenced to life in prison for the rape of the same woman's younger sister.
Asaram was arrested in 2013 after a sexual assault case was filed against him by two of his followers, who accused him of raping their daughter.
Police said he summoned the victim to his room in his spiritual retreat in Jodhpur, Rajasthan, under the pretext of "treatment" and then raped her.
وأضافوا أن المعلم أجبر الضحية على القيام بأفعال جنسية معه وهدد بقتل عائلتها إذا تحدثت عن الحادث.
كما أدين اثنان من شركاء أسارام وحكم عليهما بالسجن لمدة 20 عاما فيما يتعلق بالقضية.