Berrin was sentenced to 12 years and six months by a court in Freiburg, while Christian, the boy's stepfather, was jailed for 12 years. They saw their sentences trimmed because they helped lead authorities to the other abusers.
The woman's 39-year-old male partner was handed a 12-year prison term followed by "preventive detention", which could delay his release on the grounds that he poses a danger to the public.
The abuse was filmed and the crimes were carried out over a two-year period.
Six others are accused of being part of the paedophile ring in which the boy was abused.
A Swiss citizen and three German men who also abused the boy, now aged 10, were jailed between eight to ten years.
The mother's partner, who already had a previous conviction of serious child abuse, confessed to the court in June that he was the "driving force" behind the crimes.
A German court has handed down lengthy sentences to the parents convicted of selling their son to paedophiles on the darknet..
In May 2015, the couple started abusing the woman's son, with the man at first offering the child cash.
In the following months, the court said, the woman organized assaults on a 2-year-old girl she occasionally looked after.
The verdict against the mother and stepfather in the case, which police have called one of the most atrocious they have investigated, is expected on Tuesday.
The mother was often near the scene of the abuse by other men "to exert a calming influence on her child", and in the case of one client participated herself, the court said.
The couple must now pay £38,000 in damages to their son and to a three-year-old girl, who they also sexually abused.
"A local youth welfare office took custody of the child in March 2017, when it became known that Christian L. - who is subject to a child contact ban - was living in the same house", Deutsche Welle reported.