A court heard Matthew Stevens, 30, abused the trust placed in him by his boss who “treated him like a son” after he took him on as a school leaver and trained him to be a book keeper.
Stevens plundered the firm’s accounts over a 13-month period to fund his addiction to online gambling.
Leeds Crown Court heard Stevens became a key customer of bookies Betfred during his offending.
The court heard the case has been referred to the Gambling Commission over claims that the firm offered him free bets and days out to go gambling despite racking up huge losses.
Stevens was jailed for three years, four months over the deception.
The court heard Stevens was employed by business owner Mahmood Mazhar who trained him in accounting and book keeping.
He became an in-house accountant for two of Mr Mahmood’s businesses - Core Telecommunications, based in Stanningley, and Norman Bar, on Call Lane, in Leeds city centre.
Stevens had access to bank accounts, was responsible for paying creditors and was responsible for paying staff wages.
The court heard Stevens “bled” company bank accounts dry by transferring money to his own accounts and covering it up with fictitious transactions.
Martin Robertshaw, prosecuting, said Mr Mahmood first became concerned when creditors began contacting him to say they had not been paid.
Stevens managed to reassure his boss that errors had been made on the part of others.
The victim was then contacted by Her Majesty’s Revenue and Customs (HMRC) over an unpaid tax bill of £250,000.
Stevens continued to lie and faked online documents which he claimed was proof that HMRC had made a mistake.
Stevens plundered £850,000 from the two businesses over a 13 month period before the offending came to light.
The sum was lost as a result of Stevens’s addiction to online gambling.
Stevens, of Thorn Grove, Rothwell, pleaded guilty to two offences of theft from employer.
John Bachelor, mitigating, said Stevens became “hooked” on online betting after he lost a sum of £13,000.
Mr Bachelor said Stevens’s main betting account was with Betfred. He added that the case has since been referred to the Gambling Commission over their conduct towards Stevens.
The lawyer said Betfred would contact Stevens and offer him free bets after he had lost large sums of money.
Mr Bachelor added: “The money was taken and the money was stolen and the defendant has used that money for gambling and not to fund a lavish lifestyle.”
He added that Stevens always intended to repay the money with his winnings but it soon became clear that he would not be able to put the situation right.
The court heard Stevens went missing after going into a “spiral of depression” when he realised he would be caught.
Recorder Abdul Iqbal, QC, said: “You knew the intimate workings of this business and you must have known the impact of bleeding those bank accounts dry.”
After the case, Mr Mahmood said: “I feel devastated by what he has done to me. I trusted the guy the completely and gave him a great opportunity and he still did this to me. Fortunately both businesses have survived despite this betrayal.”
A spokesman for Betfred said: “Betfred would look to review its operating procedures should any learning points emerge from this or indeed any case. However there is no evidence to suggest that any enticement of any kind was a factor in this case.”