From today children can travel for free on weekends on Auckland Transport's bus, train and some ferry services.
To ride for free, children aged from 5 to 15 need to use a registered Auckland Transport HOP card with a child concession.
Children under five already travel for free with a paying adult.
Auckland mayor Phil Goff said the free travel would encourage the next generation of public transport users.
"Making public transport free for under sixteens on weekends and public holidays will encourage more people to leave their cars at home and use existing capacity.
"Every person on public transport is one less car on the roads, helping to reduce carbon emissions and traffic congestion."
A council spokesperson said it could take up to 72 hours after registration for the concession to be applied.
Free public transport for children will also apply on public holidays.
The change is part of a $1.1 million contribution from Auckland Council towards public transport initiatives announced earlier in the year.