The officer, detective senior Constable Greg McDougall, was injured about 5pm on Friday while approaching a wanted man in Belmont, east Perth, who was driving a white Toyota Hilux.
Police allege the driver, 37-year-old Brendan Ross Green, accelerated when the officer approached his car, striking and critically injuring him in the process.
His colleagues treated him at the scene before paramedics arrived.
McDougall, 46, was taken to Royal Perth Hospital where he remains in a stable condition with critical injuries in the intensive care unit (ICU).
“His family have been through a really rough night,” WA Police commissioner Col Blanch told 9News.
“We didn’t know the seriousness of the injuries, we’re all extremely concerned.”
Blanch said McDougall suffered broken ribs and a broken arm and was having difficulty breathing.
Green then crashed at the intersection between Clayton Street and Roe Highway where he allegedly tried to flee.
He was arrested a short distance away from the scene.
Green, from Stoneville, was charged with three offences including driving causing grevious bodily harm.
He appeared in Perth Magistrates Court on Saturday and remains in custody.