The 34-year-old has made 54 league appearances for the Ospreys during his four seasons at the Liberty Stadium.
But he will draw the curtain on his Ospreys career at the end of the season in a bid to be closer to his family in his native New Zealand.
""I have enjoyed my experience with the Ospreys on and off the field," said Holah.
"But I feel it's time to move back home to be closer to my family and friends and to enjoy playing for my home province again.
"To be honest I'm just going to see how it all goes. I'm coming off a long season here and will go straight into another quick season there with Waikato.
"So I'll just have to assess and see how the body's holding up after that, but it's been surprisingly good so far.
"The main thing is I'm still really enjoying playing rugby and still feel I've got something to offer.
"I am excited about the opportunity to return to Waikato later this year.
Holah will be back in action against Munster on Saturday night before their regular season finale against Aironi Rugby on May 6.
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