The Swiss-based drug company says the closure will be done in phases and be completed by the end of 2014.
The plant, which manufactures contact lens solution, has been in the suburb west of Toronto since the early 1980s. Once it's closed, production will be transferred to a plant in Fort Worth, Texas.
"It's important to note that 300 jobs are not moving to Texas," said Mark Smithyes, head of government affairs and market access for Alcon Canada, a division of Novartis.
"The production is being absorbed into our Fort Worth plant but we're not looking at hiring additional workers."
Smithyes said employees at the Ontario operation were told of the shutdown on Nov. 4, and management is working to assist them through the transition. Novartis still has its head office and another plant in the Mississauga-area.
He said the closure does not signal that the company is pulling out of Ontario.
"The reason for the closure is that we're continuously reviewing and adapting our manufacturing to reflect the changing market dynamics and enhance our competitiveness," Smithyes said.
"We feel that by optimizing our global manufacturing operations, we can improve productivity, reduce the complexity and free up resources for reinvestment in growth areas of our business in future technologies."
Earlier this week, Kellogg Co. announced it was shutting the doors of its cereal plant by the end of next year, cutting more than 500 full-time jobs.
The plant, which had been in London, Ont., for nearly 90 years, had been steadily reducing the volume of cereal it produces as it faced declining sales. While Kellogg's has moved into new markets, most of its profit still came from its cereal division.
Last month, food producer Heinz also eliminated 740 jobs when it announced it was closing its plant in Leamington, Ont. The ketchup maker had been in Ontario's tomato capital for more than a century.