Fees will start from 8.30am on Saturdays rather than 11am.
The council is also introducing paid parking on Sundays from 9am-3pm and on-street parking will be standardised at $1.70 an hour.
Off-street parking will be standardised at $1 an hour, or $5 a day. Motorists can still park for one hour free at the King Street car park.
The council says the changes will make more parking available.
Last year, after the Covid-19 lockdown, it offered free parking in the city for a couple of weeks.
"We quickly learnt that people parking all day in the city centre took away spaces for customers," acting transport and infrastructure manager Geoff Snedden says.
Businesses have been asking the council to do more to encourage customers to visit.
"We want to encourage people to spend more time in our city centre and support local businesses. Introducing additional paid parking hours will discourage people from using 'all-day' parking in the city centre and allowing more spaces for customers.
"This higher turnover of vehicles is good for shoppers to grab their takeaways or stay a bit longer - while also helping businesses by bringing more people into the city centre."
Snedden says the increase in revenue is forecast around $400,000 annually.
"While residents will be paying for the additional hours too, 46 per cent of spending in our city centre actually comes from people who don't live here. By having a user-pays model it means they're helping to fund some of our city's key services, rather than ratepayers or residents alone."
Snedden says the council is investigating a parking strategy that will look at the types of parking offered in the city, hours, time limits, fees, and consider concerns raised by businesses and residents.
He says the strategy is likely to be presented to the council within the next year.
The council's Facebook post announcing the changes attracted more than 750 angry emojis.
The parking changes were adopted by the council on April 7. All elected members voted for the parking hour changes, except for mayor Grant Smith and deputy mayor Aleisha Rutherford who abstained.
The motion was moved by Susan Baty, seconded Karen Naylor.
In his report on a review of fees and charges, strategy manager - finance Steve Paterson said the Local Government Act allowed the council to set parking fees by council resolution and special consultative procedures were not required.
The change.org petition can be signed here.