A woman wishing to remain anonymous left a donation for $5000 at the Wairarapa SPCA Op Shop late last week.
Op shop volunteer Ross Nixon said the woman's gift had been inspired by a fundraising initiative that he launched earlier this week.
Since Mr Nixon had gone public with the initiative, which will see weekly donations going into the Wairarapa SPCA's bank account for a year, five people had signed up.
Wellington SPCA chief executive Steve Glassey said the "incredibly generous" donation would go towards supporting Wairarapa animals in need.
"It is wonderful to receive such a generous gift and I'd like to personally thank the donor for getting behind us."