The 27-year-old actress was a guest at the 'A Small World' event at the Gstaad Palace Hotel attended by media mogul Harvey Weinstein, Meryl Streep's daughter Mamie Gummer and actors Rightor Doyle and Waris Ahluwalia, reported Daily Star online.
The event included a charity raffle of luxury prizes and Mulligan was asked to nominate a charity to receive funds from the event, so she chose the Alzheimer's Society, a cause close to her heart as her grandmother is living with the condition.
Mulligan appeared to be overcome with emotion when she gave a speech, but the actress insisted she was merely out of breath after stepping outside to call her husband, Mumford & Sons frontman Marcus Mumford, and rushing back in.
"I'm not emotional, I'm just out of breath. I've been running!... Well I am emotional too," Mulligan said.
Mulligan previously said, "I am committed to helping Alzheimer's Society in any way I can. My family and I rely on the help of organisations like Alzheimer's Society to help us understand the disease and guide us in the care of my grandmother."
The gala raised a total of 58,000 pounds for the Alzheimer's Society, the leading care and research charity for sufferers of Alzheimer's disease and other forms of dementia.