The Edgell-Birdseye $10 million expansion plan is to proceed following agreement between the Government and the company.
Deputy Premier and State Development Minister Ian Taylor said the Government had given an undertaking to abolish the pricing, licensing and regulatory functions of the Western Australian Potato Marketing Authority.
"Without this action, Edgell-Birdseye would have closed the plant," Mr Taylor said.
"This move secures the 100 jobs at the Manjimup facility. It will mean the annual production of the plant will increase to 50,000 tonnes of potatoes within the next two to three years - half of this will go to the export market.
"When in peak production, the factory will generate about $40 million a year which will flow back into the community."
Mr Taylor said although there was an inquiry going into the future of the Potato Marketing Authority, its findings would have been too late to save the Manjimup plant.
The company faced the situation where it had to commit $1 million immediately to capital expenditure or shift its operations to the Eastern States.
"This Government will not allow the existence of obstacles to the company's operation to result in 100 jobs being thrown on the scrap-heap and a valuable food processing and export industry shut down," Mr Taylor said.
"It is appropriate that the inquiry into the Potato Marketing Authority should continue but now against the background of this decision, which is not to totally disband the Authority."
The Deputy Premier said the general community stood to gain from the Government's decision - consumers could expect to pay less for potatoes, processors and distributors would be happy with the decision and Manjimup's future would be assured.