Hammington (28) has signed for Otago for the next two years and will bring experience to the halfback position for the blue and golds.
Otago coach Ben Herring said Hammington was a great addition to the Otago squad.
"Kayne coming aboard with Otago is fantastic news for the region. Kayne brings a wealth of experience and a skill set that suits the way we endeavour to play," he said.
"He will no doubt make a big impact on and off the field, and is a very well respected character."
Hammington was born in Upper Hutt and played his junior rugby in Wellington, making his first-class debut for the Wellington side in 2012. But he shifted to Manawatu two years later and was a big part of Manawatu winning the Championship in 2014.
He signed with the Highlanders in 2017 and has been the No2 halfback behind All Black Aaron Smith.
Hammington, who linked with the Zingari-Richmond club when he arrived, said it was an exciting year for Otago rugby.
"I'm looking forward to wearing the Golden O. Everyone in Otago has been really welcoming during the last few years and I looking forward to spending more time here," he said.
Otago was in the market for a halfback. Josh Renton has moved to Italy and signed a two-year deal with the Zebre team while Samoan halfback Melani Matavao, who played this year after coming to the province late and playing for the Harbour club, is not expected back.
He has signed with the Asia Pacific Dragons.
Kurt Hammer, who started the bulk of the games for Otago this year, has also signed with the Asia Pacific Dragons in Singapore but is expected to be back for the Mitre 10 Cup season.