The Edinburgh-based business, which also has shop in York, is planning to expand further with a Harrogate store.
Ness was set-up by Adrienne and Gordon MacAulay in 1997. Managing director Kenny Baillie joined in 2013.
Its merchandise includes bags, coats, jackets and blazers, featuring in statement colours and prints, including tartan as a nod to its Scottish heritage.
The £5m-turnover firm employs 10 people in its Edinburgh head office and has 11 stores nationwide.
It is now looking to expand to 30 stores following the YFM investment.
The deal will enable Ness to expand at a rate of four stores a year.
Its Ilkley store is set to open mid-July, with Harrogate launching later in the year, Ms MacAulay said.
Ness began as a mainly tourist-targeted brand, but began developing its womenswear line four years ago.
“We’re a brand that has a flavour of Scotland, but is quite unique and thoughtful in womenswear,” she said.
It chose York as its first store outside of Scotland, which has since been followed by shops in Bath and Cambridge.
Ms MacAulay said: “We went to York to reach a city that has a University, tourism and an affluent clientelle.
“But I think there’s a nice synergy of personalities between the Scots and Yorkshire.
“Customers have responded really well, they love the products. It was a good first step into England.”