Police issued 21,866 pre-charge warnings nationwide in the 2011/12 financial year, freeing up around 37,000 police hours, Police Minister Anne Tolley said.
Mostly the warnings were for disorderly behaviour, liquor ban breaches, shoplifting, and fighting in a public place.
The time saved was the equivalent of 21 additional frontline officers, Ms Tolley said.
The warnings reduced the flow of new charges to district courts by 12 per cent - saving police time preparing court files, Mrs Tolley said.
Pre-charge warnings for low-level offences were introduced nationwide in September 2010.
Police can arrest a person, take them to the station for processing, and if appropriate and the offender admits guilt, police can issue a warning as an alternative to a charge or prosecution.
The warning goes on the offender's record and is included in police crime statistics.
"Police are getting these offenders off the streets and out of volatile situations, punishing them, and by using discretion are making sure they don't clog up our judicial system with offences, which would probably have led to diversion," Mrs Tolley said.
Nearly 80 per cent of those who received warnings were not re-arrested for a subsequent offence within six months, which showed "offenders are taking the pre-charge warnings seriously".
Pre-charge warnings can only be issued by an officer of Senior Sergeant rank or above and is not available for more serious offending, including family violence and methamphetamine, Superintendent Wally Haumaha from Police National Headquarters said.
The streamlined system has even drawn praise from Sensible Sentencing Trust spokesman Garth McVicar.
"I don't have too many problems with it."
Mr McVicar said he was happy the offending still appeared on police stats and offenders' records but feared the warnings would be extended to more serious crimes.
