Ascot officials were planning to have 4,000 racegoers each day, from June 15-19, under current national policy as coronavirus restrictions ease during step three of the Government's road map.
However, the meeting has been added - alongside the second cricket Test at Edgbaston in England's series against New Zealand - to the list of pilot events to take place before the possible lifting of all legally-imposed measures to curtail the pandemic, on June 21.
Among the pilots so far staged, a crowd of more than 20,000 was permitted for this month's FA Cup Final at Wembley.
A statement from Ascot read: "Ascot Racecourse, the British Horseracing Authority (BHA) and the Racecourse Association (RCA) announce today that Royal Ascot (June 15-19) has been selected to be part of the Events Research Programme (ERP) on behalf of the sport.
"While the precise detail of what will be trialled and what the requirements from visitors to the racecourse will be remains work in progress, it is confirmed today that 12,000 people will be admitted each day to Royal Ascot.
"As details are confirmed by the Department for Digital, Culture, Media and Sport (DCMS), and following input from Public Health England and Ascot's Safety Advisory Group, they will become available on: www.ascot.co.uk
"Today's announcement means that all those who rolled over their 2020 bookings can now be accommodated, and an allocation of Royal Enclosure Badges and Queen Anne (General Admission) tickets will go on sale this Friday, May 28.
Ascot chief executive Guy Henderson said: "We are delighted that Royal Ascot has been accepted to play its part in the next phase of the Government's Events Research Programme. We much look forward to welcoming 12,000 racegoers each day.
"Our thanks go to our industry bodies, the British Horseracing Authority and the Racecourse Association, which led the preparation of the submission to Government."
BHA chief executive Julie Harrington added: "It is excellent news that Ascot will be included in the Events Research Programme as a pilot event.
"It is an opportunity to demonstrate how racing events are perfectly suited to safely hosting spectators in greater numbers as we progress through the Government's roadmap for the easing of lockdown restrictions.
"We are grateful to DCMS, and this outcome reflects the strong and positive relationship between racing and Government. Working with colleagues, we will ensure that our participants remain protected to the same degree that has been achieved with racing's bespoke coronavirus protocols since resumption in June 2020."
RCA chief executive David Armstrong said: "I am so pleased that Royal Ascot has been selected as part of the ERP program.
"The RCA and the Industry Return of Spectators Group have worked closely with the ERP (and its predecessor groups) to develop pilot options across racing which demonstrate the safe nature of the racecourse environment and the strength of our operating protocols.
"The Ascot team have done an outstanding job in configuring the course for this pilot, and racegoers and participants alike can look forward to an exceptional Royal Ascot experience delivered to the highest standards of safety."
Ascot director of racing and public affairs Nick Smith reiterated the course's gratitude to those who helped as pilot status was sought - and confirmed the task to contact 2020 ticket-holders is about to begin.
"A lot of credit (must go) to the BHA, the RCA for helping us get this over the line," he told Sky Sports Racing.
"The Government is obviously very pleased with our submission and see very clearly that an event like Royal Ascot - which is spread over such a huge site, so much of it outside, so much track and parade-ring viewing - suited their programme well.
"At the end of last week, because we were unsure whether we were going to get the go-ahead for this pilot, we'd begun the process of informing our rollover customers - those who had Royal Enclosure badges or Queen Anne, general admission badges - that in all likelihood some of those badges would be balloted out.
"So we set the unfortunate groundwork for that process. Now it's a process of going back to those people and saying 'We're really pleased to be able to tell you we're 12,000, you're top of the list, you've already got your tickets or your badges, (so) whatever you bought for 2020 is now valid for 2021'."
Most are expected to take up the offer, and Smith added: "I should imagine those on the rollover will be very keen to come - but of course, if they're still uncomfortable about coming, they have the opportunity to take a refund or to roll over again until 2022.
"Once we've sorted that side of things out, we go on sale on the 28th, this Friday, for both Royal Enclosure and Queen Anne - and we'll be able to welcome many more people than we thought we may be able to.
"It certainly is (going to be busy couple of weeks). It will be an interesting period - we still haven't got all the details, for example, of the testing procedures that are going to be required.
"But it's safe to say that everybody who comes on site - whether they're a participant, or a visitor, or working on the site - will have to return a lateral flow test, at the bare minimum."
The arrangement of pilot events, which have so far taken place elsewhere, appears to have gone well.
Smith said: "It really has - which is why the Government has given the green light to these phase two events now, with much larger crowds.
"This will help build the data they need to try to get things back to normal as soon as possible.
"That won't happen overnight, on June 21 - I'm sure of that. But it'll be a phased approach to letting more and more people in, and the data from these events is going to be absolutely pivotal.
"So we're very, very pleased to be able to play our part in that.
"I wouldn't normally be so bold - but I'd say we're quite confident that it will be quite popular, and we'll have nearly 60,000 people on the site during the week.
"It's going to feel like a normal Royal Ascot, just a bit of a mini one."