Samatha McIntosh riding Equitta at the Budapest Horse Show last year. © Béla Cziglányi
McIntosh, 33, has spent 13 years riding professionally in Europe, representing Bulgaria for the last nine years after gaining citizenship.
McIntosh is considered the most successful international showjumper to come out of New Zealand and has been ranked as high as 17 on the International Equestrian Federation (FEI) rankings.
"It's a big step but something I have wanted to do for some time," she said. "Everyone wants to ride for their own country."
McIntosh opted for dual citizenship (Bulgaria and New Zealand) when the opportunity arose to ride a great horse - Royal Discovery - at the 2000 Sydney Olympics and on which she also finished 13th at the World Cup final in Las Vegas the same year.
"I don't regret it for a minute," she said. "It was a long term situation that worked out very well."
It was thanks to her holding the dual citizenship and a change in rules that she was able to switch back to New Zealand.
With the official side taken care of, McIntosh, originally from the Waikato, will not be able to ride at a championship show for two years. With the Olympics just over, her timing is perfect as the next World Equestrian Games do not take place until 2010 but she will miss out on the European championships.
"Having Sam back under New Zealand nationality is a tremendous boost for our international showjumping future," Equestrian Sports NZ high performance manager Warrick Allan said.
"Sam's international competition results add considerable talent to our high performance progamme and we look forward to her potential involvement in future World Games and Olympic showjumping teams."
McIntosh has previously ridden for New Zealand, but most of her top level riding has been done for Bulgaria, including the Sydney Olympics and a host of European and world championship events.
McIntosh has recently moved to a new base near Cologne, in Germany.
I'm very happy to have the official side all done and that hopefully I can help New Zealand showjumping in the future," she said.