Claire Semmens, 28, handed the child to known sex attacker Aaron Hughes, who abused the boy - even using the babysitter's own room to carry out some of the abuse.
Semmens, of Cardiff, admitted causing a child to engage in sexual activity and possessing indecent images.
Aaron Hughes admitted rape and possessing indecent images of children.
'It almost defies belief that any human being would do such a thing to such an innocent young child.'
Hughes and his boyfriend had moved into the flat next door to Semmens, and had quickly become friends with the childminder.
However, it is believed Claire became attracted to Hughes and thought that by giving him children - who she looked after for her job as babysitter - he might want to have a relationship with her.
Hughes conducted sex attacks on the young boy and filmed the abuse so that he could watch it back on his computer.
Condemning the pair's actions, Judge Philip Richards said: 'It almost defies belief that any human being would do such a thing to such an innocent young child.'
'You, Semmens, made that child available not once but twice to your paedophile friend and permitted him to carry out his vile activities with that young child in your bedroom.'
He added that her breach of trust was probably worse than Hughes, given that she was in charge of the child's welfare.