The company, which will list on the NZX and Australia's ASX next month, is looking to raise up to $77.5m through the deal.
That includes $30m in new capital, which will be used to pay down debt and fund infrastructure investments.
Existing investor Direct Capital is selling up to $45m of shares, while major shareholder Oregon Group is reducing its shareholding to approximately 40 per cent, selling $800,000 of shares into the offer.
Other existing minority shareholders are selling up to $1.7m of shares, the company said.
King Salmon operates eight sea farms in the Marlborough Sounds, which harvest and process more than 6000 metric tonnes of salmon annually.
Three new sea farms, which the firm received consents for in 2014, are expected to double annual production, the company said.
King Salmon, whose brands include Ora King and Regal, has forecast operating earnings before interest, tax, depreciation and amortisation (ebitda) of $19.2m for the year to June 30, 2017.
Revenue is expected to reach $130.1m in the same period.
Dividends of $5m are expected to be declared in the 2017 financial year, rising to $5.6m in 2018.
That implies gross dividend yields of 4.5 per cent and 5 per cent, respectively.
A broker firm offer opens on October 3.
A priority offer of $1.5m worth of shares is also available to eligible residents in the Marlborough and Nelson Bays regions, the firm said.
The offer is being managed by First NZ Capital and Macquarie Capital.