NSW police on the South Coast will be conducting compliance checks on drivers with ACT number plates following the lockdown from Thursday at 5pm.
They have already been checking drivers to ensure Sydneysiders don't breach orders and head down south, threatening the health of South Coast communities.
Deputy NSW Premier John Barilaro warned ACT residents trying to escape lockdown by heading to the coast would face "large penalties".
"Stay-home orders will apply to anyone who was in Canberra on or after 5 August," he tweeted on Thursday.
"Stop the spread and don't leave Canberra. I'll be asking Commissioner Fuller to ramp up police resources on the South Coast looking for blue and white number plates. Large penalties will apply."
Mr Barilaro's electorate of Monaro extends from Queanbeyan down to the Victorian border.
