Charlie Stevens, 18, sustained an irreversible brain injury after being run down on Friday night in Goolwa, about 90km southeast of Adelaide, SA Police Deputy Commissioner Linda Williams told reporters.
Police say the 18-year-old driver failed to stop at the scene but was found nearby.
He has been charged with causing harm by dangerous driving, aggravated driving without due care, leaving the scene of a serious crash and failing to truly answer questions.
The man has been refused bail and will face Christies Beach Magistrates Court on Monday.
Premier Peter Malinauskas said the thoughts of all South Australians were with Commissioner Grant Stevens, his wife Emma and their children.
"Grant Stevens has served South Australia as a member of South Australian Police for over 40 years," Mr Malinauskas said.
"His whole life he has dedicated himself to protecting others, protecting South Australians from evil, protecting us from disease.
"He has shown extraordinary leadership in some of the most difficult circumstances this state has ever confronted, and it is just so unjust that he and his family have now had to endure this great tragedy themselves."
Ms Williams said Charlie was an apprentice carpenter who had recently finished school.
Major crime detectives are continuing to investigate the incident.
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