West Midlands Police issued a £10,000 fine after discovering up to 50 people had attended the event in Wolverhampton.
Guests had travelled from as far afield as London for the pre-planned party in Blakenhall on Saturday which included hired marquees, DJ decks and live musicians, the force said.
Police footage of the event shows an officer approach a man who appears to be the host of the event.
“I’m christening my small baby,” he says. “We’re having a little bit of a party.”
When the officer tells him that all of his guests have to immediately leave the premises, he complains: “Oh my God I’ve spent too much on this party. Give me just one hour.”
Another officer attempts to explain the Covid-19 restrictions around large gatherings and mixing households, but the man says he does not believe in the virus because “it’s no harm”.
West Midlands Police said the household was served with the notice of a “£10,000 super fine" – the first time such a fine has been issued at a residential property in the region.
“This was a reckless breach of Covid rules at a time when the deadly virus is spreading and harming our communities,” said Superintendent Simon Inglis from Wolverhampton.
"It was clearly pre-planned and bringing together this many people at a residential property is not only illegal, but increases the risk of any infections being passed on.
"We’re fully aware this is a really difficult time for people, but we won’t be able to control this disease and return to a sense of normality if we allow such events. This is not about stopping people’s fun and celebrations, but it is about saving lives from this awful virus.
"The vast majority are following the guidelines and having to make personal sacrifices. There are people unable to attend funerals and say goodbye to loved ones while abiding by the restrictions.
“So we must make a stand when we do come across blatant, and unnecessary, breaches such as pre-planned large parties. It is unacceptable and we will take action.”
Councillor Jasbir Jaspal, the City of Wolverhampton Council’s Cabinet Member for Public Health and Wellbeing, added: “Every single one of us has a key role to play in the fight against Covid-19, and the vast majority of Wulfrunians are doing a brilliant job in following the measures which are in place to prevent the spread of coronavirus.
“The sacrifices they are making day in, day out, are helping to keep infection rates as low as possible, and I am sure they will be as disgusted as I am at the actions of others who, through their thoughtlessness, are putting people’s lives at risk."