Lisa Crawshaw, stole the staggering amount over a five-year period to fund her own luxurious lifestyle with numerous expensive horses and equestrian equipment.
The 45-year-old's deceit only came to light when the company started to receive debt collecting letters, following its sale.
Miss Crawshaw, of Gainsborough, told police her habit of buying horses had become more addictive than drugs.
Crawshaw was sentenced to five years in prison when she appeared at Grimbsy Crown Court today.
Detective Sergeant Ben Robinson, from Humberside Police's economic crime unit, said: "Fraud can be an extremely distressing offence to become a victim of, especially when the level of offending is of the magnitude in this case.
“It is clear that Lisa Crawshaw had no regard for her employers and instead defrauded them to fund her own luxuries.
“With a habit of buying horses ‘more addictive than drugs’, as said in her own words, Miss Crawshaw not only destroyed a successful North Lincolnshire business, she also destroyed the owners’ years of dedication and future financial security.
“Investigators from our asset recovery team continue to make enquiries into any assets that have been gained as a result of Lisa Crawshaw’s criminality.
“She will now have the next few years in prison to reflect on her actions, and I do hope this goes some way to bringing the victims a sense of closure."