King Charles and Camilla, the Queen Consort, have invited 850 people to the 6 May ceremony in recognition of their charitable contributions.
The group includes 450 British Empire Medal recipients and 400 young people from groups chosen by the Royal Family.
Julian and Maria Sturdy-Morton, who ran a lockdown food delivery service, said it was "humbling" to be asked.
At the beginning of the Covid pandemic, the couple set up a network connecting wholesalers, who were struggling to stay afloat, with households unable to secure a supermarket delivery or get to the shops.
Quality food which would otherwise have gone to waste reached 500 households in south west London, including 100 people who could not afford to pay.
The group's army of volunteers also organised cooked meals for the neediest in their community, including care home residents, thanks to donations.
Mr Sturdy-Morton, 70, told the BBC: "We wanted to help people off the radar, people who church groups and so on would say 'they won't ask for help', because they were the ones who were going to be in the worst condition and worst situations."
In January 2022, the pair were awarded the British Empire Medal (BEM), which recognises contributions of service to the community in a local area.
"I think that we were given an award for the work of 150 people," Mr Sturdy-Morton said, paying tribute to the volunteers who contributed to their lockdown effort.
Asked how they reacted to finding out they had been invited to the coronation, Mrs Sturdy-Morton, 71, said they thought it was a hoax.
"Julian phoned me and said: 'Have you looked at your emails?' And I said no," she told the BBC.
"He said: 'Well, we've got this email, I think it's a scam'."
When they realised it was genuine, the couple "burst into tears", and both said the experience was daunting and surreal, but exciting.
"It felt like you couldn't write it, very strange, very emotional... because it's so unexpected," Mr Sturdy-Morton added.
Another attendee will be record-breaker Max Woosey, dubbed "the boy in the tent", who raised more than £750,000 for North Devon Hospice by camping in his garden for three years.
The 13-year-old from Braunton, Devon, first pitched his tent in March 2020 with the aim of raising £100, inspired by his neighbour and friend Rick Abbot, who died of cancer in February 2020.
He went on to set a Guinness World Record for the biggest sum raised by camping, with the proceeds paying for 16 community nurses in north Devon.
Buckingham Palace said that many of the 450 BEM recipients chosen to attend the coronation had been "instrumental in providing services and support to their local communities during the Covid-19 lockdowns".
Four hundred young people have also been invited to watch the ceremony via a "special private screening" in St Margaret's Church, a smaller 12th century church close to Westminster Abbey.
Half of them are from groups handpicked by the King and Queen Consort, namely the Prince's Trust, the Prince's Foundation, Barnardo's, the National Literacy Trust and the Ebony Horse Club.
The rest will come from organisations chosen by the government in recognition of the stewarding and first aid services they are to provide on the day - the Scout Association, Girlguiding UK, St John Ambulance and the National Citizen Service.
The young guests will also be able to see the coronation procession leaving Westminster Abbey at the end of the service.
The late Queen was a royal patron of the Scout Association, Girlguiding UK and Barnardo's.
The Chancellor of the Duchy of Lancaster, Oliver Dowden, said those invited had "gone above and beyond for their local area, and... will now have the chance to represent those communities at a seminal moment in our history".
The official coronation service invitation, which was designed by heraldic artist Andrew Jamieson, was unveiled earlier this week.