The billboard - for Weatherproof Garment Company - looms over Times Square, showing a rugged and determined-looking president in the brand's dark jacket while on a visit to the Great Wall in China during an official trip last year.
"A leader in style," it says underneath.
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New Yorkers and tourists have been snapping photos and staring at the poster, which stands out even in the neon jungle of New York's teeming centre.
Some applauded the aesthetics of the most photogenic president in years against a stunning landscape.
"He looks nice. He's president, but he looks nice," one man said.
But others thought the ad was in bad taste.
Billboard 'disrespectful'
"It's disrespectful. He's a young man with a beautiful family, but I don't see why he should be portrayed in any other way than as our president," Jo Ponsonby, a former bartender, 59, said after taking a picture on his throwaway camera.
With a tireless schedule of press conferences, speeches and public appearances, Obama is an almost permanent media presence.
He pops up daily on everything from cable news channels to low-grade gossip tabloids.
But Weatherproof's use of the image - a photograph shot by the Associated Press news agency during the China trip - angered the White House just a day after an animal rights group used First Lady Michelle Obama's image in a campaign.
"The White House has a longstanding policy disapproving of the use of the president and first family's name and likeness for advertising purposes," spokesman Ben LaBolt said.
'No endorsement' from Obama
A White House official said the administration had contacted "these organisations to ask that they stop using these advertisements as they misleadingly suggest the approval or endorsement of the President, First Family or White House that it does not have".
In the case of Michelle Obama, her image appeared in an anti-fur photo montage of US celebrities, also including TV hostess Oprah Winfrey, by the group PETA. "Fur-Free and Fabulous!" the ad declared.
"We did not consent to it," said Michelle Obama spokesman Semonti Stephens.
Weatherproof's president, Freddie Stollmack, has defended the jacket billboard, insisting he had "no intention of taking it down".
"We're not demonstrating that Obama is endorsing our product. We are just basically very happy to see that after 100 years we finally got a stylish president," he told ABC television.
Whether the ad will sell many jackets for Weatherproof is open to question.
Obama's image 'ubiquitous'
But few New Yorkers walking through that corner of Times Square failed to notice the billboard hanging over a Red Lobster restaurant.
"Wow. Did he agree to do that?" asked Erin Crom, a 26-year-old singer.
Crom said that because Obama is so ubiquitous she was not especially shocked at his face being hijacked to sell clothes. "He's everywhere".
Student Marquis Burkes, 19, agreed that Obama was a "celebrity." But he said he was made uncomfortable by the billboard.
"It does bother me. It's weird. He's our first black president and I feel not offended exactly," he said. "But I frown upon it."
