Ngāi Tahu Property chief executive Tony Sewell is to leave the company at the end of the year.
The company is the commercial arm of Te Rūnanga o Ngāi Tahu and has assets of about $600 million.
Mr Sewell has worked with the iwi for 21 years and was involved in the negotiation of the Ngāi Tahu Settlement, which was signed in 1996.
He said there were a number of challenges facing the newly formed company in the beginning.
"To be in a position to be respected in the various communities as being capable of doing the job. Iwi hadn't gone out before that and started to do property development work and subdivision work and things like that so they were the challenges.
"We had some great advisors on the way though and we picked up some great opportunities as we ferreted around the market and it's been pretty good."
Mr Sewell said his legacy would be the establishment of what he called a pretty sound business.
"With a good solid reputation and I think the iwi is in pretty good stead."
Ngāi Tahu Property chair Barry Bragg said Mr Sewell had played a key role in successfully growing the company.
"It is now one of the most experienced participants in the South Island property sector."
Mr Sewell will assume the role of director of major projects at the end of the year to help the new chief executive in the transition period.
He said he also plans to seek new business opportunities including directorships and consultancy work around strategic property advice.
He said being involved in the negotiation of the Ngāi Tahu Settlement was one of the highlights of his life and one he would never forget.