Galina Kovalenko, 52, was arrested in a sting operation as she allegedly tried to hand over the unnamed girl for $10,000 (£8,050).
Kovalenko, who taught literature and Russian and Ukrainian languages, is suspected of concocting the plan for almost a year and specifically targeted a vulnerable girl.
Police were tipped off over the summer and an anti-human trafficking unit in the eastern Kharkiv region put the teacher under surveillance, according to Ukraine’s interior ministry.
The buyer allegedly hinted that the girl's organs would be removed, asking about the girl's health and paying the teacher 1,000 hryvnia (£31) for photos of the girl and her medical records.
Ukraine has long been a major hub for human trafficking in Eastern Europe, with previous reports of criminal gangs preying on impoverished people to harvest their organs.
More than 160,000 people have been trafficked from Ukraine since the independence in 1991, according to the International Organisation of Migration (IOM), making the country one of the largest source countries in Europe. Internal trafficking is also a growing problem.
Countries of destination are diverse; the main ones include Russia, Poland, Turkey, Czech Republic, Italy, UAE, Germany and Israel. Victims face sexual exploitation, forced labour and forced begging, as well as occasional cases of organ trafficking.
There have been 777 recorded cases of human trafficking in Ukraine since the beginning of 2016 alone, says Iryna Lutsenko, a Ukrainian MP, who admits that more efforts are needed to solve the problem.
A court in the eastern city of Kharkiv has however remanded her in custody for two months pending her trial.