Premier Steven Marshall says pausing community activity will significantly reduce the risk of the virus spreading further.
"We need this circuit breaker, this community pause. We are at a critical point, but we will get through this," he said.
Police Commissioner Grant Stevens said the six-day period would be followed by another eight days of continuing restrictions.
From midnight all schools will close along with universities, pubs, cafes and food courts.
Regional travel will be banned and aged care centres will go into lockdown.
Factories will close, along with the construction industry.
Wedding and funerals will be banned. All outdoor sport and exercise will be banned, and masks will be mandatory outside the home.
Chief Public Health Officer Nicola Spurrier said the so-called Parafield cluster had only grown by two cases to 22.
Seven more people are waiting on test results.