A date has been set for the first Victorian state byelection in almost six years following the departure of long-time Liberal MP Ryan Smith.

Lower house speaker Maree Edwards confirmed she received Mr Smith’s official resignation on Friday.

A writ for a byelection will be issued for the seat of Warrandyte on August 26.

“I thank Mr Smith for his contribution to the parliament over the past 16 years and wish him well with his next steps,” Ms Edwards said.

The Victorian Liberals have preselected former Box Hill candidate and daughter of Malaysian-Chinese migrants Nicole Ta-Ei Werner to run for the seat in Melbourne’s outer northeast.

The charity manager and former youth pastor beat 22-year-old law student Antonietta Di Cosmo and Institute of Public Affairs senior fellow John Roskam.

If successful, Ms Werner would become the 10th woman in the state Liberals’ 30-member party room following outspoken MP Moira Deeming’s expulsion after she participated in an anti-trans rights rally attended by neo-Nazis.

Held by the Liberals on a 4.2 per cent margin, Warrandyte could prove a hurdle for Opposition Leader John Pesutto if Labor decides to contest it.

Labor hasn’t won a byelection in Victoria since taking the seat of Benalla from the Nationals in 2000.

The winner is expected to be sworn in during the first sitting week of state parliament in October.

– AAP