The Royal British Legion's Riders Branch was founded from an ex-services motorcycle club in 2004 and now boasts more than 4,250 members all over the country and abroad.
Around 80 bikers, many wearing leathers adorned with their service medals, drove into the grounds of the royal household and parked their vehicles in a long line on the gravel in front of the house.
Prince Charles posed for photographers in front of the bikes and was even persuaded to sit on one - a Yamaha Venture Star 1300.
As one of the bikers turned its engine on, the Prince gave a look of mock astonishment as heavy metal played from it, and made a joke about the choice of music.
After meeting some of the bikers outside, Charles went inside Clarence House for a drinks reception, where he chatted to more of the branch members.
The event, which was meant to be a garden party but had to be held indoors due to the rain, came about at the Prince's request after he met some of the bikers at Wootton Bassett in January last year.
Members of the Riders Branch have been present at more than 100 repatriations and have appointed their own repatriation liaison officer to offer support to families.
Bill Haley, 51, who served in the Army for 10 years but is now a police sergeant in Devizes, Wiltshire, said he met Charles on his visit to Wootton Bassett.
He said: ''This was his way of saying thanks to us for all the fund-raising we have done.
''He asked us what we thought about moving the repatriations to Brize Norton and I said it wouldn't be the same.
''I said there wouldn't be the same atmosphere that there is at Wootton Bassett and he said it was a shame.''
Anna Bradley, 44, one of the branch's 200 female members, said it was ''absolutely brilliant'' to be invited to Clarence House and meet Charles, who she described as a ''funny guy''.
Mrs Bradley, a Ministry of Defence worker from Bovington, Dorset, said: ''I'm so, so proud to be a part of it.
''He was very interested in what we actually do - our fund-raising, our raising the profile of the British Legion, and how we support the guys who are currently on operation in Afghanistan.
''Also, what other activities we get involved in. I told him that, basically, if there's a possibility we can ride a motorbike to it, we will do.''