The actor was among the bidders hoping to buy Tully's Coffee, a Seattle, Washington-based company facing closure, and save 500 jobs.
Dempsey has now revealed his bid of $9.2 million (£5.8 million) was accepted and he is looking forward to revitalising the firm.
He says in a statement, ""I'm thrilled that we won and I'm even more excited about saving Tully's Coffee and its hundreds of jobs. Tully's is a great company with committed employees, and with its base in Seattle, one of the world's greatest cities, I'm confident we will be able to successfully build the brand and help grow the economy...
""Seattle has been very good to me over my career, and I am honoured to have the privilege to own Tully's and work closely with the company's employees.""
Representatives for Starbucks, another coffee chain which started in Seattle, were also among the bidders.
The sale will be formally approved by a judge on 11 January (13).