Mr Robertson said he now wanted to spend more time with his family and planned to start theology studies. "It is always something that has interested me."
Although some had suggested he run for the Auckland Council, he did not want to swap one seven-day-a-week job for another so would stand for the local board instead. "Local issues have become more important than national politics. We need effective local representation."
Mr Robertson, who is also Assistant Speaker, said he still hoped his members' bill to introduce a parliamentary code of ethics would be drawn out of the ballot before he left after five years of trying.
He would otherwise try to find another MP to inherit it from him. Asked if MP Trevor Mallard was one option, he laughed and said he might instead try Su'a William Sio.
Mr Robertson's retirement plans open up a safe Labour seat for another candidate. He would not say who he hoped would succeed him.
"South Auckland is a very special place. I have four Sikh temples, at least three mosques, a Hindu temple, a Buddhist temple and many, many Christian churches. It's the spiritual centre of the country."
In the past, Labour list MP Shane Jones has eyed standing in a general electorate, but has now said he wants to seek selection in Tamaki Makaurau again in 2014 to try to win the seat from the Maori Party's Pita Sharples.
The seat could also be a good fit for broadcaster Shane Taurima.