The bird, which appears on the New Zealand cider brand's products, is also the country's national emblem.
However, its population has decreased by 99 per cent over the past 80 years, meaning there are now only 50,000 left, the agency said.
To draw attention to this issue and raise money for conservation, Packham and Strachan, who first appeared on children's TV programme The Really Wild Show in 1986, returned for a one-off wildlife special entitled ‘The Kiwi Wild Show’.
As part of the campaign, which ran between September and October, the presenters trekked through the wilderness to meet a team of experts from conservation charity Kiwis for kiwi to highlight the threat of extinction the species faces.
The programme has been viewed almost 130,000 times on YouTube, while the wider campaign achieved more than 80 pieces of coverage in the online additions of national newspapers, including in the Daily Express and Daily Mirror.
Packham and Strachan were also interviewed on ITV's breakfast show Good Morning Britain.
As a result of the campaign, visitors to the charity's website doubled to 4,176 between September and October versus the same period last year, while regular donors from the UK increased from five last year to 42 in the last two months, Cow said.
it also helped bring in corporate donors, such as UK removal firm John Mason International Movers, which pledged to donate money for each household it relocates. According to Cow, this will result in an additional $5,000 (£3,700) to support kiwi conservation this year.
Cow PR, Packham, and Strachan were paid for their involvement in the project, the agency said.