Victor Marke, aged 59, of Mavis Avenue, Ravenshead, denied four counts of historic indecent assault on a teenage girl.
He and his wife Zara Phythian, 36, of Taurus Close, Mansfield, denied 14 allegations of sexual activity with another child.
The jury at Nottingham Crown Court returned their verdict just before 1pm today, following a trial which began on April 28.
Judge Mark Watson told both defendants he would decide their status, and when they will be sentenced, at 2pm this afternoon.
The jury took about one day to reach their verdict after the case was summed up by the judge yesterday morning.
Zara Phythian – whose legal name is Marke – appeared in hit Marvel movie Doctor Strange, alongside Benedict Cumberbatch.
When questioned by police officers, she said: "I am not a paedophile or a rapist, nor is Victor. I just feel sick right now and angry."
The girl, who is now an adult, told police that the couple filmed most of the abuse in an attempt to recreate pornographic scenes.
She said the first offences happened after the couple gave her alcohol to drink, and Ms Phythian dared her to give Mr Marke oral sex. She said Mr Marke then had sex with both of them.
"I knew it was wrong but I just didn't know how to get out of the situation or say anything," she told police.
As the abuse continued, she said Mr Marke threatened to smash her kneecaps if she told anyone.
"He just said nobody would believe me if I told them anyway," she told police. "They always had a power over me."
The couple were both martial arts instructors in Nottinghamshire at the time.
The court previously heard police found videos of Zara and Victor Marke having sexual encounters with other men, but no videos of them with other girls were found.
When asked how his alleged victim knew about sex toys he and his wife used, Victor Marke said she could have found them. Victor Marke admitted having sex with the girl – legally and consensually – when she was 18, on four occasions, and said ‘it made me feel young again’.