Following the 2020 general election, the Greens agreed to cooperate with the Labour majority government, and Shaw was re-appointed as the Minister for Climate Change.

Between 2011 and 2014, Shaw worked as both a consultant for HSBC bank on "environmental awareness programmes for future leaders" and also at Wellington social enterprise the Akina Foundation.

[11] In the 2011 election, Shaw stood in the Wellington Central electorate, succeeding Sue Kedgley as the Green Party candidate in this seat.

[14] Shaw has said that in the 2011 Greens selection process, party members "didn't have a lot of time to get to know me" and disregarded him as "an ex-PWC management consultant in a suit".

[16] He also unsuccessfully contested the Wellington Central, coming third place to Labour's Grant Robertson and National's Paul Foster-Bell with 5,077 votes.

[19] Despite having only been an MP for seven months, Shaw successfully contested the election against longer-serving MPs Kevin Hague and Gareth Hughes and extra-parliamentary candidate Vernon Tava.

[4] The day after becoming co-leader, he called for a cross-party consensus on climate change and said there was room for the Greens and National to work together on the issue.

[22] He also said in his first major speech that he wanted the Green Party to be "more like modern New Zealand", and expand its membership both in terms of numbers and to include a more diverse group of people.

[4] The leadership pairing of Turei (a lawyer) and Shaw (a management consultant) pitched itself as a more mainstream, professional version of the party compared to previous incarnations which were associated with "being wacky, smoking dope, hugging trees and eating lentils.

[26] Under pressure, she eventually resigned on 9 August, leaving Shaw as the Green Party's sole leader for the duration of the 2017 general election campaign.

[35][36][37] As Minister for Statistics, Shaw received criticism from National MP Nick Smith for the low response rate during the 2018 New Zealand census.

[39] In April 2018, Shaw as Minister for Climate Change expressed support for the Government's decision to end future gas and oil exploration, hailing it as the "nuclear-free moment of our generation."

He also reiterated the Green Party's support for ending deep-sea oil and gas exploration, stating that "fossil fuels are not our future.

"[40][41] According to figures released by the Department of Internal Affairs, Shaw was the government minister to spend the most on air travel fares in late 2018.

Shaw clarified that these air travel fares had been spent on attending multiple international climate change conferences.

[51][52][53] In late August 2020, Shaw attracted criticism from the opposition National Party, school principals, teachers unions' and members of his own Green Party after he approved the allocation of NZ$11.7 million from the Government's $3 billion COVID-19 "shovel-ready" recovery fund to the private "Green School New Zealand" in Taranaki.

[54][55][56] According to Newshub, Shaw refused to sign the Government's NZ$3 billion "shovel-ready" infrastructure fund until the Green School in Taranaki was approved.

[58][59] On 3 September, the Education Minister Chris Hipkins disputed Shaw's claim that he had given verbal approval to the allocation of NZ$11.7 million to the private Green School in Taranaki.

[60] On 2 November, it was reported that the owners of the Green School had reached a settlement for the Government's NZ$11.7 million grant to be converted into a loan; a development that was welcomed by local principals.

[63] He also contested the Wellington Central electorate, coming third place to Labour's Grant Robertson and National's Nicola Willis.

Despite this, Labour and the Green Party agreed a "cooperation agreement" on 31 October 2020 that resulted in Shaw retaining the Climate Change portfolio and become Associate Minister for the Environment (Biodiversity).

[65][66][67] At the 2021 party annual general meeting Shaw was challenged for the co-leadership by Dunedin climate activist and software developer, James Cockle.

[69] In mid September 2021, Shaw attracted media attention after Prime Minister Ardern granted him and a team of nine diplomats spaces in the managed isolation and quarantine system to attend the upcoming 2021 United Nations Climate Change Conference summit in Glasgow.

[77] In late November 2023, Shaw assumed the Green Party's climate change, finance, public services and regulation spokesperson portfolios.