Over the next 10 years, the spirits company will redevelop the site in Parkhead, Glasgow, with new maturation warehouses and a blend centre.
New bottling lines and packing equipment will also be added.
Bacardi chief executive Andreas Gembler said the expansion was to cope with demand in emerging markets.
"Demand for Dewar's premium whiskies has grown significantly, especially in Asia and other emerging markets where the brands were launched only in the past three years," he said.
Bacardi bought the Dewar's brand in 1998 and since then has expanded the portfolio to include Dewar's 12, 15 and 18 Year Old, Dewar's Signature and Aberfeldy single malt.