A UK court found the Nigerian senator, his wife and a doctor lured a 21-year-old man to Britain with the promise of a job, but intended to take his kidney.
A court in London has convicted three people for a "horrific" plot that tested Britain's new modern slavery laws.
Nigerian Senator Ike Ekweremadu, 60, and his wife Beatrice, 56, were found guilty in an organ-harvesting scam. Another Nigerian, Dr Obinna Obeta, was also found guilty and described at the trial as the "medical middleman".
Jurors at the Old Bailey, Britain's top criminal court, heard how a 21-year-old man from a remote village in Nigeria was tricked into believing he was travelling to the UK for a job.
Instead, the plan was to harvest his kidney and transplant it into Sonia Ekweremadu, the 25-year-old daughter of the accused couple, who fell ill while studying in the northern city of Newcastle.
She was cleared of any wrongdoing.
The couple arranged a visa for the victim - who cannot be named for legal reasons - while Dr Obeta organised his travel to Britain and hosted him in south London.
A private medical company was used to help arrange the victim's visa.
He earned a few pounds (euros) per day selling mobile phone accessories, believing he was employed by the Ekweremadu family.
However, the court heard how they had in fact arranged an £80,000 (€90,000) private transplant at London's Royal Free Hospital, with a health tourism company acting as a go-between.
After several medical appointments, the victim realised he was to donate his kidney, with doctors testifying he had no idea why he was at the hospital.
The victim later returned to his accommodation in south London, but found the mood had changed, with the family treating him as a "slave", he testified.
After a few days, he escaped from the house and slept on the streets.
In May, the victim walked into Staines Police station and said: “I don’t know anywhere, I don’t know where I am. I was sleeping three days outside around, for someone to help me, save my life.”
The man is still being safeguarded by the police.
"This was a horrific plot to exploit a vulnerable victim by trafficking him to the UK for the purpose of transplanting his kidney," said Joanne Jakymec, Chief Crown Prosecutor.
“The defendants showed utter disregard for the victim’s welfare, health and well-being and used their considerable influence to a high degree of control throughout, with the victim having a limited understanding of what was really going on here,” she continued.
Beatrice Ekweremadu was arrested at Heathrow Airport in June, while Dr Obeta was arrested at his home address.
They will be sentenced at a later date.
Sonia Ekweremadu, who was due to receive the kidney from the victim, remains on dialysis with a critical medical condition.
The six-week trial was the culmination of a fast-paced investigation by British police.
"This conviction sends out a clear message across the world, the UK will not tolerate the international industry in illegal organ removal," said Leading investigating officer, Detective Inspector Esther Richardson from the Metropolitan Police.
“We could not have achieved this conviction without the help of one man, the victim survivor. I commend him for his utmost bravery.”
Senator Ike Ekweremadu and his wife Beatrice - who both reside in the Nigerian capital Abuja, were found guilty of conspiracy to arrange/facilitate travel of another person with a view to exploitation - namely organ harvesting - Section 2 Modern Slavery Act 2015.
“Modern slavery is all around us," said Richardson. "We need the public’s help in identifying potential victims of trafficking and exploitation to bring offenders to justice and protect the vulnerable.”