Arguments on the sentencing will be held on December 19 in the Tis Hazari court.
Shashi Singh had claimed that she never lured the victim to Sengar's residence and said she herself was a victim of his cruelty.
The court pulled up the CBI for taking a year's time in filing the chargesheet.
The verdict comes on the day when the most horrific gangrape took place in the national capital 7 years ago.
The Unnao rape case had put the Yogi-led BJP government in the dock for not taking quick action against the Bangermau strongman. The case had triggered massive outrage across the country, especially for the manner in which the police had allegedly tried to shield the lawmaker and his brother Atul Singh and the insolent attitude shown towards the victim and her family.
The rape complaint was filed only after the distressed woman staged a protest outside Chief Minister Yogi Adityanath's Lucknow residence and threatened to self-immolate if justice wasn’t served.
The woman was kidnapped and raped by Sengar in 2017 when she was a minor. Sengar, a four-time BJP MLA from UP's Bangermau, was expelled from the BJP in August 2019.
The court had on August 9 framed charges against the MLA and Singh under Sections 120 b (criminal conspiracy), 363 (kidnapping), 366 (kidnapping or inducing a woman to compel for marriage), 376 (rape) and other relevant sections of the Protection of Children from Sexual Offences (POCSO) Act.
The offences entail maximum punishment of life imprisonment.
On July 28 this year, the car of the survivor was hit by a truck and she was severely injured. The woman's two aunts were killed in the accident and her family had alleged foul play.
Her father was allegedly framed in an illegal arms case and arrested on April 3, 2018. He died while in judicial custody a few days later, on April 9. The local court here has framed murder and other charges against the MLA, his brother Atul and nine others in the case.
The woman and her family is provided CRPF security as per the apex court's orders. They have now been shifted to a rented accommodation in the national capital with the assistance of the Delhi Commission for Women (DCW).
(With inputs from Agencies)