The news comes one week after Dell unveiled plans to buy EMC, the world's largest data-storage provider, for USD 67 billion in a record tech tie-up.
Western said the acquisition will help transform it into a data storage solutions company "with global scale, extensive product and technology assets, and deep expertise."
The merger of the two California data storage firms would create a company combined global sales of more than USD 21 billion last year.
SanDisk especially brings to the union capabilities in NAND memory, common in USB flash drives and other memory cards.
More From This Section
The takeover comes just on the heels of Western's agreement to allow China's Unisplendour Corp, a state-controlled technology investment and development firm, to take a 15 per cent share in Western.
That appeared to contribute to the decision announced Monday that China's Ministry of Commerce to remove restrictions on Western's China business that arose when it took over Hitachi's hard drive business in 2011, which made the company the world's largest disk drive maker.
"The combined company will be ideally positioned to capture the growth opportunities created by the rapidly evolving storage industry."
The deal values SanDisk at USD 86.50 a share, 23.6 per cent higher than the shares were on Friday before the first reports of a deal surfaced.
Western will pay for the takeover largely with borrowed funds, but stressed its "strong track record of integrating acquisitions to create value."