Mariusz Stepien was searching a field near Peebles with friends on 21 June when he found a bronze object buried half a metre underground.
The group camped in the field and built a shelter to protect the find from the elements while archaeologists spent 22 days investigating.
Among the items they found were a complete horse harness – preserved by the soil – and a sword that have been dated as being from 1000 to 900 BC.
Mr Stepien said: “I thought I’ve never seen anything like this before and felt from the very beginning that this might be something spectacular and I’ve just discovered a big part of Scottish history.
“I was over the moon, actually shaking with happiness.
“We wanted to be a part of the excavation from the beginning to the end.
“I will never forget those 22 days spent in the field. Every day there were new objects coming out which changed the context of the find, every day we learned something new.
“I’m so pleased that the earth revealed to me something that was hidden for more than 3000 years. I still can’t believe it happened.”
As he was getting strong signals from the earth around the initial object, Mr Stepien contacted the Treasure Trove Unit to report his find.
They also found decorated straps, buckles, rings, ornaments and chariot wheel axle caps.
Evidence of a decorative “rattle pendant” from the harness was also discovered – the first one to be found in Scotland and only the third in the UK.
The hoard has been moved from the site in a large block of soil and taken to the National Museums Collection Centre in Edinburgh.
Emily Freeman, head of the Treasure Trove Unit overseeing the recovery and assessment of the find, said: “This is a nationally significant find – so few Bronze Age hoards have been excavated in Scotland.
“It was an amazing opportunity for us to not only recover bronze artefacts, but organic material as well.
“There is still a lot of work to be done to assess the artefacts and understand why they were deposited.
“We could not have achieved this without the responsible actions of the finder or the support of the landowners.
“The finder was quick to action when they realised that they had found an in-situ hoard, which resulted in the Treasure Trove Unit and National Museums Scotland being on site within days of discovery.”
David Harvie, Queen’s and Lord Treasurer’s Remembrancer (QLTR), said: “This Bronze Age hoard is highly significant and promises to give us a new insight into Scotland’s history.
“I would like to thank the finder who discovered these wonderful items and whose quick actions in contacting the Treasure Trove will ensure these objects can be properly preserved and studied.”
Similar hoards are very rare in Britain though two famous examples are from Parc-y-Meirch, Denbighshire, and Heathery Burn Cave, Co Durham. Only one type of similar hoard is known from Scotland, which was found at Horsehope Craig, Peeblesshire. The Horsehope hoard was found in 1864.