A man sent abusive, threatening and offensive letters to Lord Alan Sugar that were "deeply derogatory" towards the Jewish faith, Essex Police has said.
Patrick Gomes, 70, sent three letters to Lord Sugar's business premises in Loughton, Essex, in 2018.
Gomes, of Lytellton Road, Leyton, east London, was convicted on Wednesday at Chelmsford Crown Court in his absence.
He is due to be sentenced on 23 December.
Gomes was convicted of one charge of religiously-aggravated harassment, putting those targeted in fear of violence.
A warrant was issued after he failed to appear at court, police said.
He was arrested on Thursday and remanded in custody, ahead of sentencing.
'Simply not acceptable'
It said Gomes was arrested in March 2019 at his home after his DNA and fingerprints were found on one of the letters, each of which was addressed directly to Lord Sugar.
Officers found additional letters written by Gomes, all of which were discriminatory in nature, and the address that the other letters had been sent to in his address book.
The businessman and star of The Apprentice said he had been reluctant to refer the matter to "already stretched" police but thanked officers for "helping to shine a light on the fact that this type of behaviour is simply not acceptable".
PC Marc Arnold, the investigating officer, said: "Nobody should ever be subjected to this level of abuse or fear physical violence because of their faith.
"I'm really pleased that justice has been rightly served.
"There is simply no excuse for any hate crime and if this happens to you or you witness this type of behaviour, please tell us - we will not tolerate racism or discrimination of any kind and neither should you."