In 1985, she moved to Wellington, where she worked with Labour MP Fran Wilde on the Homosexual Law Reform Bill before taking up a position as an advisor to Burke in the office of the Minister of Employment in 1986.

[4] In the 1996 election, the Lyttelton electorate was abolished, and Dyson stood in Banks Peninsula, losing to Carter, who had in the meantime become an MP through winning the 1994 Selwyn by-election.

[7] She acknowledged after her resignation that she had been convicted and fined for possession of cannabis when she was a teenager stating "I find it sickening that some 25 years later someone has anonymously passed this information to journalists.

In her valedictory statement in 2020, Dyson reflected on the Act: "I regret that it wasn't more prescriptive in its implementation, because its roll-out has been slower than it could have been.

"[9] In a reshuffle on 31 October 2007, Dyson was promoted to Minister for Social Development, which she held until the Clark government lost power at the 2008 general election.

During this time Dyson held a range of portfolios, including health (2008–2011), internal affairs (2011–2013), conservation and disability issues (2013–2015), Canterbury Earthquake Recovery (2013–2014) and senior citizens (2013–2017).

[14] Dyson was criticised in December 2015 for describing National's Speaker David Carter as "incompetent, biased... lazy [and] sexist" on Twitter.

[15][16] Dyson had been positioned to be Deputy Speaker of the House of Representatives (to Trevor Mallard) if Labour won the 2017 general election.

[17] While Labour was able to form a Government (in coalition with New Zealand First), the National Party's Anne Tolley was appointed as Deputy Speaker instead.

[23] In March 2023, Dyson was accused of not being politically impartial in her roles as deputy chair of the Earthquake Commission and Fire and Emergency New Zealand as is the expectation of public servants and government-appointed board members.