Tatiana Lozano Pereira, 32, admitted to killing her son Itaberli Lozano in Cravinhos, Sao Paulo.
According to local reports, Pereira had long rejected her son because he was gay.
They had an explosive row at Christmas after which Itaberli moved in with his grandmother.
Pereira pretended to forgive him and, on December 29, urged him to return home.
However she had secretly hired hitmen Miller da Silva Barissa, 18, and Victor Roberto da Silva, 19,
to kill her son. She hid them inside her home under orders to attack him when he entered.
However they failed to kill him and so she grabbed a kitchen knife and stabbed her son to death.
According to local reports, Pereira and her husband, Alex Pereira, 30, the victim's stepfather, then took her son's body to an abandoned area and burned it.
The victim's paternal grandmother reported his disappearance to police.
Officers became suspicious because Tatiana had not reported him missing herself and seemed surprisingly indifferent about his disappearance.
His charred remains were eventually found on January 7, in a nearby field. Police also seized two knives from the house.