Loch Duart, founded in 1999 and with about 60 employees across its operations in Sutherland, provided fish for the royal wedding last year and the Diamond Jubilee celebrations.
It also counts a wide range of fine dining restaurants, including Gordon Ramsay at Claridge's in London and the Dornoch Castle Hotel, among its customers.
Now Loch Duart is being backed by the Scottish Investment Bank (SIB) and Capicorn Investment Group and will use the money to upgrade equipment and infrastructure plus invest in business development.
Alan Balfour, Loch Duart commercial director, said: "We're in a fortunate position. Demand for our product is growing all the time. We need to expand our operations to keep up with that demand and to continue competing on an international level.
"This funding means we can make the changes we need to make while safeguarding jobs and, as we expand, creating new ones."
Loch Duart has gained a strong reputation for sustainable practices and was the first salmon farm in the world to be approved by the RSPCA-backed Freedom Food scheme.
It already sells to countries such as the US, Germany, Japan, Singapore and South Africa.
Earlier this month it was on a trade mission organised by Scottish Development International and Scotland Food and Drink to look at opportunities in China, Japan and across Asia.
Mr Balfour said: "We've been largely self-funded and we've grown into an important organisation in a Scottish market.
"We needed help to make the next step, and thanks to SIB and Capricorn we're now in a position to take it. We're looking forward to continuing to push ourselves over the next few years, and to seeing our company continue to develop and grow into an international force."
Kerry Sharp, acting head of SIB, said: "Loch Duart has achieved a great deal. It has an excellent reputation and growth potential.
"With the right help at the right time, this company could go from being a highly successful Scottish concern to being a major player in the international fish production market."