The actor, who was dubbed "McDreamy" by fans of the hospital drama while his co-star affectionately has been called "McSteamy," won a bankruptcy auction to buy Tully's Coffee, a small coffee chain based in Seattle.
"I'm very excited -- there's a lot of opportunity here for us and for the employees to keep this company intact," Dempsey said. "But now we have a lot of work to do... we have a good plan and I think in time we'll turn things around."
Among those Dempsey beat out is Tully's much bigger Seattle neighbor, Starbucks Corp., which wanted to convert the cafes to its own brand.
Dempsey, whose company Global Baristas LLC plans to keep the Tully's name, declared victory on the social media site Twitter with the message: "We met the green monster, looked her in the eye, and...SHE BLINKED! We got it! Thank you Seattle!"
The win for Dempsey deals a rare setback for Starbucks on its home turf. Starbucks has long been both praised for bringing "coffeehouse culture" to the U.S. and criticized for crushing smaller chains. The coffee giant, which had planned to convert the Tully's cafes to its own brand, last month announced plans to expand its global footprint to 20,000 cafes over the next two years, up from the current 18,000.
Dempsey said in an interview on Friday that as the underdog in Seattle, Tully's will need to find its identity.
"It's a much smaller chain that has a lot of potential that hasn't been given the proper care," he said.
But in a statement shortly after the auction on Thursday, Starbucks insinuated that Dempsey shouldn't celebrate just yet.
Starbucks, which wanted to convert the Tully's cafes to its own brand, said that a final determination on the winning bid won't be made until a court hearing on Jan. 11. Starbucks said it's in a "back-up" position" to buy 25 of the 47 Tully's cafes, with another undisclosed bidder making an offer for the remainder.
The combined bids of Starbucks and the undisclosed bidder come to $10.6 million, above the $9.2 million Dempsey's company is offering to pay through his company, which was formed in order to purchase Tully's. The other investors in Global Baristas aren't being disclosed.
But Dempsey was confident the judge will allow him to buy the company.
"I do feel that we're going to get this company, certainly, and we're going to keep it intact, we're going to keep these jobs alive which is very important."
Watch: Dempsey visits a Tully's store in Seattle on Friday:
The announcement came after a day that Dempsey said was filled with the slow process of negotiations and featured several emotional swings.
"There were a lot of twists and turns during the day when we felt we were up, then it felt like we were losing it -- it was very emotionally draining, and of course the stakes were so high," Dempsey said. "We care very deeply about this company and we really want it and we want to turn it around, so you're dealing with all those emotions. Any time there is a bid that comes in, it's a lot to process, emotionally."
The star actor says he planned to be very involved in the running of the company, adding that the immediate challenges were to address bookkeeping issues, staff morale and sprucing up the coffee shops.
"Our employees need to have a morale boost, they need to feel confident," he said. "I need to get to know them and I need to get to know the communities and I need to spend a lot more time here. I really like it here, I like waking up and being in this town."
Once the business is stabilized, Dempsey said the long-term goal would be to take the chain national.
"We can pull this off. We just have to take steps that are slow and smart," he said. "I'm going to get behind the counter. I'm going to serve coffee...I'm going to give the company a boost of energy."
Seattle has a special place in Dempsey's career - "Grey's Anatomy" took place in a fictional hospital in the city. And although Dempsey lives in Los Angeles, he plans to spend more time in Seattle to where it will be like a second home to him.
"I have a very strong connection to Seattle," he said. "We talk about it on a daily basis and I see images on a daily basis when I go into the sound stage. I feel at home here, I grew up in a small town in Maine and it reminds me a lot of that so I like it a lot and it's a good excuse to spend more time here, honestly."
Dempsey said he believed there is room in the city for Tully's and the much larger Starbucks; he noted there might be people who are rooting for the underdog.
"In a society where there are so many big corporations that swallow the little guy, we thought, let's not let this happen to this company," he said.
Tully's Coffee, which has more than 500 employees and locations in Washington and California, filed for Chapter 11 bankruptcy protection in October, citing lease obligations and underperforming stores. TC Global Inc., its parent company, said in a release Friday that it was "encouraged and excited" about Dempsey's commitment to the chain.
Tully's President and CEO Scott Pearson called the deal a "great match" and that the goal is to make sure creditors get paid and to keep as many people employed as possible.
Also in the running to buy Tully's was Baristas Coffee, which operates a chain of drive-thru espresso stands featuring female employees in skimpy outfits.