Mohammed Zaman, aged 52, who ran the Indian Garden restaurant in, Easingwold, North Yorkshire, was jailed for six years in May last year over the death of customer Paul Wilson, from Sheffield.
The 38-year-old suffered a severe reaction after eating a chicken tikka masala takeaway, which contained peanuts, in January 2014.
Despite Mr Wilson requesting 'no nuts', he was served with food which contained a groundnut mix.
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During his original trial, Zaman was said to have had a 'cavalier attitude' to safety.
The prosecution said the owner had 'put profit before safety' at the restaurants he owned and had used cheap ingredients.
He was found guilty of manslaughter and six charges of breaching food safety rules.
Zaman claimed he had not had a fair trial, and that the judge presiding over his trial had 'misdirected' the jury, but after a hearing at the Court of Appeal in London his conviction was ruled safe.
Mr Wilson had managed his peanut allergy since it was discovered when he was seven after he suffered a reaction to a chocolate bar.