Aberdeen Cook School will close on June 30 as it is "no longer commercially sustainable".
The five staff who work directly for the school were told on Wednesday and a redundancy consultation process is underway.
The TV chef launched the school in 2012 after success with his initial cook school in Port of Menteith, near Stirling.
He said: "We enjoyed a great run of custom for a number of years but like many other businesses in Aberdeen and the surrounding areas, we are not immune to the downturn in the north-east economy.
"Our corporate custom suffered in particular for understandable reasons and we have worked exceptionally hard for the last 18 months to diversify our offering, but we have now reached a point where the Cook School is no longer commercially sustainable."
He now plans to focus on expanding his pizza restaurant on the same site at Back Wynd in the city centre, and is looking into "further opportunities" for the restaurant in Edinburgh and Glasgow.