Paget was barred from all competition in October after Clifton Promise tested positive for the banned substance reserpine, a derivative of the Indian snakeroot plant, a well-known herbal remedy.
The test was conducted after Paget's victory in the Burghley horse trials, a title which passed to fellow New Zealander Andrew Nicholson after Paget's disqualification.
Paget took his case to a tribunal hearing with the world governing body, Federation Equestre Internationale, in June.
A provisional suspension was removed earlier this month, with the tribunal stating it was "satisfied on a balance of probabilities that the PR [Person Responsible, Paget] has demonstrated that he bore no fault or negligence for the EAD [equine anti-doping] rule violation".
The final ruling of the tribunal, released today, confirmed that the positive finding came as the result of contamination of an equine supplement during its manufacture, for which Paget bore no responsibility.
In acknowledging that top level equestrian sport required "the use of supplements to properly care for such elite horses", the tribunal highlighted that Clifton Promise had tested clean on four previous occasions dating back to 2010 when using the same supplement including at Badminton in May 2013.
"The tribunal therefore believes that the PR had the right to rely on the product, and in particular to expect that the product did not contain any prohibited substances."
The ruling concluded that "the tribunal finds that the PR has succeeded in establishing that he bears no fault or negligence for the rule violation" and that "the tribunal is not imposing any sanctions on the PR".
Paget had competed at several events in the UK after the lifting of the provisional suspension and today's confirmation clears him to represent the New Zealand eventing team at the World Equestrian Games at Normandy this month.
Paget said he was relieved to put his horror 10 months behind him.
"I feel as though I had my career stripped from me and now someone has said 'hang on, you can have it back'. It is complete relief," he said.
"I didn't know if I would be cleared, despite knowing I had done nothing wrong. I knew it wouldn't be as easy as turning around and saying 'I didn't do it'. I was fortunate that we were able to find the source of the contamination, trace it and prove it, and – most importantly – that I wasn't responsible nor could have known."
Paget said the support he had received from sponsors, owners, his team-mates, staff, family, friends, Equestrian Sports New Zealand and his legal team at Burges Salmon had been invaluable.
Equestrian Sports New Zealand (EANZ) president Chris Hodson QC welcomed the ruling.
"It is very important to the reputation of equestrian and New Zealand sport that no athlete should be knowingly involved in any act of doping. That Jock Paget has proved his innocence, which requires a very high standard which has only been achieved in one previous case, is intensely satisfying, and fully justifies the support which ESNZ has given him throughout."
Paget's disqualification from Burghley will remain as there was no challenge to the presence of the banned substance.
At the World Equestrian Games, Paget will join Nicholson (on Nereo or Avebury), Sir Mark Todd (on Leonidas) and Tim Price (on Wesko) in the team event. Caroline Powell (on Onwards and Upwards) and Lucy Jackson (on Willy Do) will ride only the individual event.
