The facility currently provides the supermarket with Morrisons branded sliced meats and deli products and the investment will enable it to introduce an extensive range of ready-to-eat chicken meals.
Mario Jacobs, General Manager at Farmers Boy Deeside, said the Deeside plant would have the capacity to produce 40 tons of ready-to-eat chicken meals a week supplying all 477 Morrisons supermarkets.
The Welsh Government has supported the expansion with £635,000 through the Economic Growth Fund which is designed to fast track investment projects with the potential to create jobs and stimulate the economy.
The investment at the plant, which is within Deeside Enterprise Zone, will provide an additional direct boost of around £1.5m into the local economy through an increased wages bill.
Business Minister Edwina Hart said the Welsh Government has recognised agri-food as a priority sector in the Welsh economy with the potential to grow and create jobs.
"The creation of 90 jobs and capital investment of £6.4million will be a tremendous boost to the North Wales economy and a confidence boost to Deeside and the food cluster based there.
"The Economic Growth Fund is helping deliver our Programme for Government to support growth and the creation of sustainable jobs. It has enabled this expansion to go ahead at Deeside which will bring direct and indirect benefits to the regional economy."
This latest investment follows a major expansion at the 175,000 sq ft plant last year by Morrisons, now its parent company, which saw staff numbers double from 300 to 600. It is Morrisons’ first manufacturing venture in Wales.
The current project will involve investment in new equipment and machinery, upgrading some facilities and a re-configuration of the factory floor to accommodate the new food lines and staff.
Mario Jacobs said:
"This investment will ensure that our Deeside site is equipped to meet the needs of the business as it continues to grow. We are delighted to announce this move will create up to 90 jobs and will look to fill these jobs with local candidates where possible."