[8] Following the retirement of Loraine Braham, the CLP-turned-independent member for the Alice Springs-based seat of Braitling, Giles was preselected as CLP candidate for the 2008 Northern Territory election.

[13] Willem Westra van Holthe challenged Giles at the 2015 CLP leadership ballot on 2 February and was elected leader by the party room in a late-night vote conducted by phone.

On 3 February, ABC News reported that officials were preparing an instrument that would allow the Administrator to use his reserve power to sack Giles and commission Westra van Holthe in his place.

[15] After a meeting of the parliamentary wing of the CLP, Giles announced that he would remain as party leader and Chief Minister, with Westra van Holthe as his deputy.

[16] After four defections during the parliamentary term including Kezia Purick, Alison Anderson, Larisa Lee and Robyn Lambley, the CLP was reduced to minority government by July 2015.

[17][18] Giles raised the possibility of an early election on 20 July stating that he would "love" to call a snap poll, but that it was "pretty much impossible to do".

In October 2015, the then Country Liberal-controlled Northern Territory Government under Giles granted the Chinese-owned Landbridge Group company a 99-year lease for A$506 million of Port Darwin.

[19][20] Concerns have been expressed over this leasing arrangement due its strategic significance, Landbridge being owned by a billionaire with close ties to the Chinese Communist Party,[21][22][23] and the port being adjacent to facilities in active use by both Australian and U.S. military forces.

For instance, a poll conducted by ReachTEL and commissioned by The Australian which surveyed 1036 residents via robocall on the afternoon of Sunday 1 March 2015 across all 18 electorates in Darwin, Palmerston and Alice Springs–almost three-fourths of the legislature–indicated a landslide 17.6% two-party swing against the incumbent CLP government since the last election.

At the 27 August election, the CLP was thrown from office in a massive swing, suffering the worst defeat of a sitting government in the Territory's history.

Giles later told AM that he had known for some time that the CLP would not be re-elected, but felt compelled to "put on a shiny face with the pearly whites" in order to maintain morale.

[38] In August 2018, Giles conducted an interview with Blair Cottrell, chairman of the far-right extremist group the United Patriots Front (UPF).

Following a public outcry, Giles's program was put "in recess", and Sky News stated it regretted featuring the interview on the channel, and that it was an "error of judgement".