At 40 years and 206 days of age, Rees became the youngest person to assume the office, a record that has since been surpassed by Dominic Perrottet.

Rees was born in 1968 in Western Sydney to parents Daryl and Frances, his mother being a longtime member of the Labor Party, reportedly from Penrith, New South Wales.

Subsequently he went on to study English literature at the University of Sydney, attaining an honours degree in 1994, supporting himself by working as a garbage collector at the same council.

[7] Rees's first job in politics was in 1995, when he became an adviser to the then deputy premier Andrew Refshauge, for whom his mother, Frances, worked.

During this period, Rees cycled between Bullaburra in the Blue Mountains, where he lived at the time, and central Sydney, a distance of more than 90 km (56 mi).

[11] As Minister for Water Utilities, Rees was responsible for implementing the $1.9 billion Sydney Desalination Plant at Kurnell, and the proposed Tillegra Dam in the Hunter Region.

A slump in revenues during the 2007–2008 financial crisis compelled Rees and the State Treasurer Eric Roozendaal to implement a mini-budget which was handed down on 11 November 2008.

[25] The next day Rees sacked Finance Minister (and Labor powerbroker) Joe Tripodi, Primary Industries Minister Ian Macdonald, and Parliamentary Secretaries Henry Tsang and Sonia Hornery for blocking key reforms aimed at distancing the government from corruption and improving the provision of services to constituents and for plotting to remove him from the premiership.

In addition to the Work Plan developed by the summit, Rees also announced the establishment of 4,000 government apprenticeships across the state and 2,000 cadetships.

From 1998 to 2008, there had only been a slight increase in the retention rate for students remaining to complete Year 12, with significant inequality as measured by socio-economic status.

[37] Controversially, Rees also introduced non-religious Ethics classes into primary schools against fierce opposition from church groups.

Despite ongoing disputes between criminal gangs, the Bureau of Crime Statistics and Research reported that in the 24 months to December 2010, ten of the 17 major offence categories were stable and seven were falling.

[45] Building on the environmental legacy of Bob Carr, Rees announced the preservation of the last remaining large tract of River Red Gums in the state's south.

[47] Rees also announced the establishment of Yengo National Park in the Upper Hunter region; 120,000 hectares of pristine bushland, in June 2009.

[53] Rees and Campbell enjoyed a close working relationship, and on their watch train service reliability rose to a ten-year high of 95% on-time running.

[56] To encourage public transport use on weekends, the Rees Government introduced $2.50 Family Fun Day fares for Sundays,[57] with discount entry to museums and other tourist locations.

The Yuin people of the South Coast of NSW had lodged a claim under the Aboriginal Land Rights Act for 20,000 hectares bordering the Morton National Park, including Yarramumum and Boolijong Creeks and parts of the Yerriyong State Forest.

This latter commitment was retained by Kristina Keneally when she took over as Premier, and it formed the central element of the Arts policy announcement in the 2011 election.

Rahman, of Slumdog Millionaire fame, to Sydney for a free open-air concert which attracted more than 50,000 people to Parramatta Park.

[70] Acknowledging Labor history, Rees and the Lord Mayor of Sydney officially renamed parts of Hickson Road, The Rocks, as 'The Hungry Mile'.

Under Premier Bob Carr, the Jackson Inquiry precipitated an ongoing fund to be established and maintained by James Hardie to provide for future payouts to sufferers of asbestosis.

[73] James Hardie made inadequate provision, and Rees intervened in 2009 to ensure that affected individuals would be able to claim into the future.

[79] In November 2009, Rees announced that he wanted to move towards public funding of election campaigns instead of a reliance on large corporate donations.

By comparison, he'd won election in 2007 with 64.5 percent of the two-party vote; he was one of several MPs from Labor's traditional stronghold of west Sydney who saw their majorities more than halved.

Both Macdonald and Obeid were found to have acted corruptly by the ICAC, who recommended the Director of Public Prosecutions give consideration to criminal charges being laid against both men.

Rees repeatedly stressed he did not feel vindicated, but rather was distressed that the Party and its members had been subject to the smear of association with those who had been investigated.

[90] In October 2014, following his announcement to retire from politics, Rees took up a position as the chief executive of the Public Education Foundation (PEF), a non-profit organisation that provides scholarships to disadvantaged students to support them to stay at school: "The public education system in NSW is very strong but this foundation will allow those kids who may not have the resources to buy the extra book or the bit of software they need.

"[91] After leaving the PEF, Rees was subsequently appointed as the National Assistant Secretary of the Finance Sector Union (FSU) in May 2017 where he worked until early 2021.