Just 3,200 tigers now live in the wild, down from 100,000 a century ago, and those that remain face a losing battle with poachers who supply traders in India and China with tiger parts for traditional medicines and purported aphrodisiacs.
Mr Putin, whose country is one of 13 that are home to the world's last wild tigers, hosted a "tiger summit" with Mr Wen and representatives from other Asian countries, the highest level meeting ever held to try to save a single species.
"It is very important to save this wonderful, imperial creature, the tiger, for future generations," Mr Putin said, adding its situation worldwide was approaching "catastrophe".
His spokesman, Dmitry Peskov, said a programme to double the number of free-roaming tigers by 2022 was approved.
Initially, $350 million will be spent over the next five years, according to co-ordinators the World Bank and conservation organisation WWF. But implementation will be key and without tough measures to halt poaching and deforestation by the 13 nations, tigers could cease to exist in the wild by that time.
WWF director-general Jim Leape said: "If we cannot succeed now, if current trends continue, by 2022 we will have only scattered remnants of the populations left."
Mr Putin - who was given a tiger cub for his 56th birthday - has tried to court Russia's growing environmental movement by throwing his weight behind efforts to save the tiger, which roams across the vast forests of Russia's Far East.
An ex-KGB spy who cultivates a macho image, Mr Putin referred to Indian freedom fighter Mahatma Gandhi's quote: "The greatness of a nation and its moral progress can be judged by the way its animals are treated."
Russia was the only nation where the number of tigers has increased in recent decades - from several dozens in 1947 to around 500 now, Mr Putin said.
However, Russian wildlife experts say that Siberian tigers are still endangered.Some 100 of them are killed annually to be smuggled to China, a senior inspector from a natural reserve in the Primorsky region said.
Conservation groups say governments and activists have failed to stop the poachers.
John Robinson, chief conservation officer of the US-based Wildlife Conservation Society, said: "If nothing changes radically we are going to see a lot of tiger populations blinking out."
Wild tiger numbers have tumbled 97 per cent in the past decade and up to four of the nine tiger subspecies have vanished.
Celebrities including American actor Leonardo DiCaprio are also committed to the campaign - he donated $1m to it yesterday.
A marker of the summit's success will be the launch of a consortium to fight wildlife smuggling, said John Sellar, chief enforcement officer for the Convention on the International Trade in Endangered Species.
He said: "The situation is now so serious that if we don't get enforcement very soon then the money that we're spending in other areas, one could almost say, is flushing down the toilet."
India is at the centre of the trade with the most seizures of tiger parts, followed by China, where nearly every inch of the tiger fetches a high price, with pelts sold for as much as $35,000, according to black market database Havoscope.
Mr Sellar added: "If someone breaks into your house at night and steals your DVD player, the insurance company is going to pay for you to go and get another. When the final tiger or leopard is gone, that's it.
"If we can't do it for the tiger, then I think we have to ask, are we going to be able to do it for anything else?"