It was the second time the self-confessed cannibal had been tried for killing Bernd Juergen Brandes in Rotenburg in western Germany in 2001. At the retrial, the court was told Meiwes, 44, slaughtered a man to satisfy his sexual urges.
He was originally convicted of manslaughter and sentenced to eight and a half years in prison in 2004, but on appeal, a federal judge threw the sentence out because it was too lenient and ordered a retrial on the higher charge of murder.
Judge Klaus Drescher described Meiwes, who sliced off his victim's penis while he was still conscious so they could eat it together, as "psychologically ill" but added that he was responsible for his actions.
In evidence, psychologists said that Meiwes was a deeply disturbed and lonely man but agreed he was mentally fit to stand trial.
The judge rejected the prosecution's demand that Meiwes be disqualified from release after serving a minimum 15 years, meaning he may not spend the rest of his life behind bars. Meiwes immediately indicated that he would appeal the sentence.
His lawyers had argued that he was not guilty of murder but rather of the crime of "killing on demand", which carries a maximum prison sentence of five years.
"Ultimate kick"
Meiwes, a smartly dressed computer technician, insisted throughout both trials that his victim had a death wish and had begged to be killed and eaten, saying it was the "ultimate kick" both of them were seeking. "He had wanted everything just the way it eventually happened," he said last week.
He met Mr Brandes through an internet advertisement for a "slaughter victim" and invited him to his rambling farm house. The Berlin based engineer, who had written a will, bought a one-way rail ticket, while Meiwes set up a beer-tent table in his house to serve as a butcher's block.
The two men made a videotape of their encounter, in it the two are shown having sex, before Meiwes severs Mr Brandes' engorged penis, which the two men fried and tried to eat. When the bleeding victim lost consciousness, Meiwes stabbed him in the throat and cut away other parts of his body.
He later admitted to eating some 20 kilograms of Mr Brandes’ flesh, in meals accompanied by potatoes and a pepper or wine sauce, served on "good crockery".
In a letter to Mr Brandes' boyfriend, Meiwes apologised for killing him but said he had met "a beautiful death."
More fantasies
Meiwes testified that his fantasies about eating flesh dated back 30 years. He said realised he wanted to eat a school friend, as a way of keeping somebody with him forever, after his father abandoned the family.
He admitted he was still having cannibal fantasies while in prison, which prosecutors said indicated a high risk he would try to kill and eat somebody again.
Meiwes was arrested when an Austrian student noticed another Internet advertisement and alerted the police. Investigators found that he had been in touch with more than 200 people who shared his fantasies, while Meiwes himself said there were about 800 cannibals in Germany who hoped to fulfill their urges.