The ankle bracelets would send a signal to Corrections staff if paroled offenders strayed into "exclusion zones" such as parks and schools.
The GPS system is allowed for under existing legislation and will be introduced in August, with 11 child-sex offenders on parole with special conditions fitted in the initial launch.
But Rape Crisis national director Georgia Knowles said the money would be better spent on education and rehabilitation.
She said 90 per cent of adult sexual-abuse cases were committed by someone known to the victim. That figure was 85 per cent for child victims.
"These sorts of measures that track small minority groups of sexual offenders are not the best way," Ms Knowles said.
GPS-monitoring of offenders occurred in the United States and placed stress on sex offenders, which made the situation worse, she said.
"Stress is a trigger for abusing."
Tauranga sexual-assault counsellor advocate Denise McEnteer said slapping GPS bracelets on sexual offenders was addressing the issue "after the horse has bolted".
"It's the soft option," she said.
"We know sexual offenders can get around all that technology.
"We need to educate youngsters to take into account the technology available and understand grooming through interactive programmes from school age, so kids question what is appropriate and what isn't," she said.
"Sexual offenders are everyday people in the community engaged in all levels of professions."
Neighbourhood Support co-ordinator for Papamoa Lorraine Stevens said the ankle bracelets would contribute to the public feeling "a lot safer".