The changes will cost $700,000 for 2017-18.
Mayor Justin Lester said it was a "no-brainer" to include those contracted for cleaning work.
"It's all contained within the 3.3 per cent proposed rates increase.
"That's despite having $5 million in additional costs from the earthquake.
"We wanted a prudent budget, a budget that was affordable, but that also ensures we treated our staff well."
He said previous experience showed paying a living wage could actually save money.
When the Wellington City Council stopped contracting for parking wardens and instead employed them directly at a living wage rate, they saved overall.
"Because previously the contractor was taking the majority of the benefit from the contract, and not the staff," Lester said.
"We've had greater loyalty from staff, reduced turnover, and increased services, at a lower burden for ratepayers."
Lester said the council was still looking at other contracts which could be brought in for living-wage pay rates.
Wellington region Living Wage co-ordinator Lyndy McIntyre said the council was the first to make a commitment to the living wage, which had given campaigners a head start.
"But we're very confident that other councils will follow Wellington's lead.
"Around the country, different councils are at different stages of bringing in the living wage."
McIntyre said Wellington still needed to renegotiate other contracts, to bring all workers on to the pay rate.
"There are still some workers at Wellington City Council who are employed through contractors, and on very low rates of pay.
"Some close to the minimum wage, others on minimum wage.
"They've committed to address those on a case-by-case basis, and we know it needs to be a staged implementation.
"So that could still take years to fully implement."
During a campaign debate in September, Lester publicly promised to roll out the living wage to contractors.
There were worries last month that the promise might not be delivered on, when the cleaning contract was put out to tender with no mention of living-wage conditions.