The fluffy baby bear has become Germany's latest merchandising sensation, inspiring Knut T-shirts, Knut mugs, Knut postcards, Knut DVDs, Knut keychains, Knut sweets and stuffed Knuts costing up to 29.95.
Born at the zoo on 5 December, Knut was rejected by his mother and hand-raised by zookeepers, though an animal rights group said he should be put down. He shot to fame thanks to TV and newspaper pictures. Since then, Knutmania has just kept on growing.
Together with Leonardo DiCaprio, he appears on the cover of Vanity Fair's current May issue, with pictures taken by star photographer Annie Leibovitz. For the German edition, he has the cover all to himself.
Officials say zoo attendance has roughly doubled on average since he was presented to the German capital on 23 March and estimate that by today, 300,000 people will have come to visit Berlin's new mascot.
"Obviously, his innocent, baby-like looks are an important reason," said Peter Walschburger, a psychologist at the Free University in Berlin, adding that Knut's white fur and soft, round features made people want to protect him.
Knut will be spending his first Easter without his beloved trainer Thomas Drflein, who is taking a holiday, and already thoughts are turning to a more independent future for Knut - and for Drflein, who told celebrity magazine Bunte on Wednesday, "Honestly, much as I like him, I am looking forward to returning to my normal life."
The merchandising frenzy includes a special collection by German toy maker Steiff, famous for its teddy bears. Since January, the company has been selling 800 Knut bears every day, said sales director Gerald Uhlich.
The stuffed animals come in three sizes and cost from 19.95 to 29.95. Steiff has a licence deal with the zoo and will invest part of its profit in projects there.
Haribo, the German sweet company that makes gummi bears, has created a white, marshmallow-like Knut sweet that will hit grocery stores across Germany and Austria next week. The company will also contribute part of its proceeds to the zoo.
"Our Knut sweets have a raspberry flavour and are sold in boxes of 150 pieces or over the counter for five cents each," Marco Alster, a Haribo spokesman, said.
Knut even has his own blog in German, English and Spanish - written by a journalist at the regional public broadcaster, Rundfunk Berlin-Brandenburg.
The zoo has registered the cub as an official brand. "Never before did we think of registering a trademark for an animal name," said Uhlich.
"But we succeeded and it works amazingly well. Within just two days, a worldwide trademark was born."
The Knut marketing phenomenon has also had a dramatic impact on the Berlin Zoo's stock. The shares, which had hovered around the 2,000 over recent years, hit 4,820 this week.
"I think investors hope that the financial situation of Berlin zoo will improve further. This is of course the reason why the shares went up so much over the past few days," said Joerg Walter of Berlin's Stock Exchange board of directors.
The boom may run its course in the next few months: unlike his stuffed replicas, cute Knut will soon grow up - into a huge and much less cuddly adult.