Krejcir, 46, and his co-accused, two of whom are part of the Hawks elite police unit, had pleaded not guilty to the charges.
This is the first conviction against the notorious mafia boss who faces four separate trials in South Africa.
Despite notorious tags by local media, Krejcir still denies links to the criminal underworld.
Krejcir was accused of ordering the kidnap and torture of Bheki Lukhele, whose brother had allegedly disappeared with 25kg (55lbs) of drugs.
He was arrested by South African police at his home in Johannesburg in late 2013 over the incident.
Krejcir made local and international headlines in July 2013 when he survived an attempt to kill him using guns hidden behind a car number plate operated by remote control.
A number of his associates have been killed in separate incidents over the years but Krejcir has repeatedly denied any involvement with local organised crime syndicates whose operations are reported to also include drug dealing.
The businessman is also wanted in the Czech Republic, where he was convicted in absentia last year on tax fraud charges.
Krejcir moved to South Africa in 2007, where he is applying for asylum due to death threats trailing him in his native country, Czech Republic.
