Kevin Harvie won the order from the oil and gas giant just two months after his Hectares Sweet Potato Crisps business started trading.
Coming soon after the company won supply deals with the Whole Foods Market retail chain and the BrewDog bars operation, the order from BP has provided a big boost for the company.
It puts Glasgow-based Hectares on course to achieve sales of more than £150,000 in its first year of trading.
Mr Harvie, 28, said Hectares has already sold 30,000 bags of crisps. These have a recommended retail price of 99p.
"It has been a fantastic start for us," said Mr Harvie. "We always knew there were consumers who loved sweet potato, we just didn't realise how many!"
The success to date has vindicated Mr Harvie's decision to take the risk of leaving his job with Grant Thornton to focus on his ambition of starting a business.
Mr Harvie became interested in the food and drink industry while working at the accountancy firm, which acts for a range of firms in the sector.
He decided to investigate the potential for a sweet potato crisp business after learning of the popularity of the snacks in the USA.
Mr Harvie found sweet potatoes were high in fibre and vitman A. This meant the crisps appeared to provide a healthier option.
After conducting basic market research among target groups like sports enthusiasts in Scotland, Mr Harvie decided to develop a crisp that he thought might appeal to consumers.
He spent a month frying home-made crisps in his kitchen after work before coming up with a version that he thought had potential.
After winning interest from specialists at Abertay University, Mr Harvie then worked with them to get the taste of the crisp right and come up with a version that might be suitable for mass production.
This proved to be good enough to win the confidence of a firm near Derby which Mr Harvie uses to manufacture the crisps.
Mr Harvie felt sanguine enough about his prospects to leave Grant Thornton last August, after spending three months on sabbatical.
He moved into the Entrepreneurial Spark start-up accelerator in Glasgow the same month.
Mr Harvie is delighted with the return he has enjoyed so far on the savings he investmed in starting the firm, which he describes as a "decent amount".
He also has big ambitions.
"My vision is to create a brand known across Europe as the sweet potato crisp brand," said Mr Harvie.
He hopes to recruit up to three staff over the next 12 months to drive sales and marketing.
With his wife expecting a baby in weeks, Mr Harvie is enjoying combining business life with preparations for fatherhood.
"It's a bit chaotic," he joked.