Mrs Rich (41) has been an MP for nine years and has bucked the party line on some occasions, but she said in her speech she was proud to have not crossed the floor on any vote.
She had not been lobbied by any member of caucus to change her vote, although members of the National Party had contacted her urging her to change.
Family played a large role in the speech of Mrs Rich. Her husband Andrew, children and parents were in the gallery to hear her last speech.
She paid tribute to the support Mr Rich had provided during campaigning in Dunedin North, not an easy place for a National Party candidate to hit the hustings.
Being an MP was an experience few New Zealanders would have but it was something she would remember for the rest of her life.
"Leaving here is hard at such an exciting time but it is the right decision for me."
Being an MP was not a job but a way of life, she said.
"Political service is all consuming and the New Zealand public deserves nothing less."
