Emergency responders arrived at the restaurant on Thursday night to find a restaurant manager who became nauseous after inhaling fumes from a powerful mix of cleaning agents, according to the Burlington Fire Department.
Ryan Baldera, 32, died at Leahy Hospital and Medical Centre.
He had recently been married and was the father of a newborn, according to multiple reports.
Ten other people, including workers and customers, were taken to hospital following complaints of difficulty breathing and burning eyes.
World news in pictures
According to Burlington Interim Fire Chief Michael Patterson, Mr Baldera was "overcome" with chemical fumes while attempting to clean up a lethal chemical combination of the cleaning product Super 8, which is composed of sodium hypochlorite, a bleach, and the acid-based Scale Kleen, which had been tipped over and spilled, unbeknown to employees.
The chemicals created a green, bubbling reaction, causing the employees' eyes to burn.
Firefighters arrived, evacuated the restaurant and alerted the state, which sent a HAZMAT team with protective clothing and air tanks to take electronic readings for hazardous materials. The restaurant will reopen following an inspection by the Burlington Board of Health.
In a statement, Buffalo Wild Wings says the company is "shocked and saddened to learn of this horrific accident at our franchise-owned sports bar and are working closely with our franchisee and the authorities while they conduct an investigation".
Auto-Chlor Systems, the manufacturer of both Super 8 and Scale Kleen, said in a statement that the company is working with the Occupational Safety and Health Administration as well as local authorities and emergency teams and "doing everything we can to determine all details behind this incident".
The company said: "First and foremost, our condolences are with the individual and their family as well as those affected yesterday during the incident. The safety and well-being of our customers are our first priority, always."
Last month, Buffalo Wild Wings announced that it had fired employees at an Illinois restaurant for asking an African American family to move tables because a white customer didn't want them there. The company said its employees will undergo sensitivity training.