On Tuesday, 1.3 million people had received the first instalment of $116.67 of the government's cost of living relief payment.
The payment is targeted at most people with a salary less than $70,000.
Christchurch City Mission communications adviser Ewan Sargent said five people donated their payments immediately after receiving them on Monday, and more donations had come through since the charity posted about it on Facebook.
"We were surprised when this happened but also really moved. We are always delighted at the support we get, but when people get a windfall, then immediately think of others, that's really quite special," he said.
One woman who donated said: "I don't need my cost of living payment this month. I feel you need it much more than I do".
Sargent said the charity's services had been in high demand this winter.
One man in his 70s felt embarrassed to ask for help after routinely donating to the mission for decades.
"He had worked all his life and now everything was unaffordable and it was getting tougher to live," Sargent said.
Christchurch City Mission fed over 4000 people in July, with almost a third of those people being children, and Sargent said their housing and social services also remained busy.
"We will be supporting a lot of people in many different ways this winter."
