[6][7] After a career as a solicitor and local councillor, Dominello was elected to the Parliament of New South Wales following a Ryde by-election triggered by the resignation of his predecessor John Watkins.

Dominello served two terms, but did not nominate for the 2004 local government elections, citing his desire to concentrate on his legal career, and subsequently let his Liberal membership lapse.

[13] On 3 September 2008, Labor Deputy Premier John Watkins, who was also the local Member for Ryde, resigned from parliament, resulting in the need for a by-election.

Dominello nominated for preselection and won, defeating Ryde Mayor Vic Tagg and several other local party members.

Additionally, the by-election came at a very bad time for the government, whose polling numbers had rapidly tailed off only a year after winning a fourth term.

The swing, at the time the largest a sitting NSW government had ever suffered, turned Ryde into a safe Liberal seat in one stroke.

[8][14] Dominello has spoken in Parliament about a number of local issues including the future of Ryde Hospital,[15] the Homebush V8 Supercar race[16][17] and the increase to the Parking Space Levy.

[24] On 18 August 2021, while fronting the media in a press conference, Dominello's face was seen to be drooping and he was blinking slowly with his left eye.

Concerned viewers contacted his office to urge him to seek medical help, which he did later that afternoon and was diagnosed with Bell's palsy.