In a social media post, Robertson - who opted out of contesting the Labour leadership after Jacinda Ardern's shock resignation - said he loved representing the electorate but he believed it was the right decision.
He said he intended to continue being the Finance Minister under the leadership of Chris Hipkins next term.
Robertson was brought to Parliament after winning the seat in 2008. He has held it for the 15 years since, which he said in his post made him the second-longest serving MP there behind only former Prime Minister Peter Fraser.
"I have loved representing this electorate," his post said.
"It is an extraordinary place - from the buzz of the CBD, to the beauty of the Town Belt, Zealandia, Mākara and Ōtari Wilton's Bush. The people are exceptional too - our dedicated public servants, the endlessly creative artists and musicians, the chefs, the film and game developers, the scientists, the students and young people, the community workers and so many more.
"I am also very proud of what we have achieved here - particularly in the development of affordable housing, starting the much needed transport improvements, protection of the Town Belt, recognition of our inner city residents, our support for arts and artists, and our support for those who fall outside the margins of our society.
"I am so grateful for the faith placed in me by Wellingtonians to have elected me five times into this job. When I won the electorate in 2008 (pictured) it was with a majority of just over 1900. Last election that reached more than 18,000. I am humbled by the support that I have received. I am especially grateful for the armies of volunteers who have been part of our campaigns. Nga mihi nui ki koutou."
National's Finance Spokesperson Nicola Willis contested the seat for National in the past two elections, but won just 17.9 percent of the vote compared to Robertson's 57.7 percent in 2020, and 25.75 percent to Robertson's 49.26 percent in 2017.
Willis confirmed last year she would instead contest Ōhāriu in Wellington's west.
Robertson said his decision would be a shock to some, and he was sorry for it, but he believed Labour was on the right track to win the election and would put forward a "terrific" candidate when one was selected.
The move also makes it simpler for Robertson to resign following the election if Labour is unsuccessful - though he did not address that in his post.
He will remain the MP for Wellington Central until the election.
