Around two in every five people who signed up to the scheme last year chose to support one of the pandas, according to figures released by the Royal Zoological Society Of Scotland, which runs the zoo.
Tian Tian and male companion Yang Guang have been a major attraction since arriving from China in December 2011.
There were hopes Tian Tian was pregnant last year but in October the zoo said she lost the cub in the late stage of pregnancy.
Penguins were also a popular choice for adopters, with about one in 12 choosing a gentoo (8%) while around the same proportion chose a rockhopper penguin (7.5%).
Meerkats were in fourth place (7%) and koalas were the fifth most popular (6.5%).
Adopters can choose from about 100 animals and receive a factsheet about the creature, regular updates and an invitation to a special annual event. Prices start from £40 a year.
At Highland Wildlife Park, Kingussie, which is also run by the Zoological Society, the Scottish wildcat is most popular for adoptions, with the rate more than doubling in the last year to comprise a third of the total (34%).
While there are no official figures for how many wildcats are left in Scotland, some reports suggest as few as 35 individual animals are left in the wild.
A plan to halt the decline of the species was launched in September, involving organisations such as the Royal Zoological Society Of Scotland. The plan is designed to reverse the fall in numbers of the species, dubbed the Highland Tiger, within six years.
The Highland park's two polar bears, Walker and Arktos, are second most popular there (15%). Red pandas are third (10%) and the Amur tigers are fourth (8%). In fifth place is the European grey wolf (7.5%).
Fiona Skiffington, assistant membership and adoption manager for the Society, said: "Animal adoption is a great way to support the aims of the Royal Zoological Society of Scotland, a charity that receives no Government funding.
The money generated by our adoption scheme is put to good use.
"As little as £10 feeds a snow monkey for one week, £20 keeps the koalas toasty warm for one day, £25 buys a penguin nest ring for breeding season, £50 pays a conservation field assistant's wage in Brazil and £100 buys valuable education materials for our work in Scottish schools."