If Steve Jobs' creation -- the device that built the tablet market -- can't revive it, maybe the actor who played him can.

On Thursday, a week before Apple is expected to release its latest iPad, Lenovo unveiled its own new tablet in London, along with a bendable laptop. They are the first devices designed with input from Ashton Kutcher, the actor and tech investor who was appointed "product engineer" for the Chinese electronics manufacturer last year. In 2013, Mr. Kutcher also starred in a biopic as the late Apple founder.

"Apple wasn't stepping up going, 'Hey, let's build a product together,'" Mr. Kutcher told Ad Age, when asked why he chose Lenovo over more recognizable brands. "I didn't want to go out and be the face of a tech company. I wanted to actually build something."

What he's building could pose a threat to more established players. Lenovo claimed 5% of the worldwide tablet market in the second quarter, according to IDC -- a 65% year-over-year jump. Apple, the leader with 27%, saw its share fall by 9% during the same period; second-place Samsung, which holds 17% share, posted growth of 2%.

With its newest tablet, the YOGA 2 Pro, Lenovo is going big. The new tablet packs a 13-inch screen and loads of bells and whistles for home entertainment -- an eight-watt sound system, replete with a subwoofer, and a built-in film projector. Mr. Kutcher takes some credit for introducing the features, after polling consumers on their tablet usage.

"We set out to make the most extraordinary entertainment experience that you could possibly have on the tablet," he said. "We built this projector into this thing that's just awesome."

Lenovo's new tablet, which starts at $499 and launches in the U.S. this month, has another first: the addition of Windows operating systems. For Lenovo, which previously relied only on Android, it's a move to widen consumer appeal -- and benefit from Microsoft's ample marketing budget.

It will also lean on Mr. Kutcher's star power. He stars in the sitcom "Two and a Half Men" and has a massive Twitter following. He appears in two 30-second spots, one each for the tablet and laptop, the YOGA 3 Pro. While the ads will be televised in some markets, the company stressed they are built primarily for online consumption. Commercials will run online in the U.S., Latin America and China, and on television in Brazil, Russia, the Middle East and parts of Europe, the company said.

Several consumer electronics companies have turned to celebrities, often for limited time periods and with limited success. Lenovo insists their employee is different.

"We didn't want to overuse Ashton," said David Roman, CMO of the company, which is based in Beijing and Morrisville, North Carolina. "Here, he was very much involved in the development of the product."

Mr. Kutcher, who says he spends 30 hours a week scouting software companies for Lenovo and in his role as an angel investor, flew to Beijing twice in the past year and held multiple meetings with Lenovo's product team in Los Angeles, as well as "countless phone calls."

This year, Lenovo has ramped up its digital marketing in the U.S., including a tie-up with The Onion that allows the brand to be the brunt of jokes. For its new campaign, Lenovo, which works with Saatchi & Saatchi and Digitas in the U.S., will run ads with Buzzfeed, Huffington Post and The Daily Beast, among other digital publications. Mr. Roman is coordinating the marketing in more than 100 countries, including Lenovo's advertising debut in Australia, his home nation. There, he said, the marketing will be 100% digital.

"Like everybody, we've been moving to digital and social," Mr. Roman said, adding that this campaign, "just accelerated the move."

Lenovo is taking on heavily-armed competitors. Last year, it spent $51 million in measured media, according to figures from Kantar Media. Apple spent $627 million, and Samsung spent $614 million.

Mr. Roman said the company will resist a challenger brand approach, in lieu of focusing on Lenovo's device innovation. "We're not trying to go after their customers," he said. "We really look at more creating that niche that is unique to us."

Part of that niche will come from Mr. Kutcher. "I have a vested interest in this product. So I'm do everything I can to promote it," he said. Although he specified that this will not include prioritizing ad inventory on A+, his online publication. "I don't run ads for Lenovo; that's not my job," he said.

In the weeks prior to its product launch, Lenovo released a handful of online videos with Mr. Kutcher discussing tablets with various groups -- senior citizens, precocious kids and entrepreneurs. Mr. Kutcher blasted the videos out to his 16.4 million plus Twitter followers.

In the final one, someone asks him if he is "just acting." Mr. Kutcher responds, "No, I'm an actual product engineer for Lenovo."

Even with Mr. Kutcher in its corner, the company is digging deep into a market -- tablets -- that is flattening. In August, IDC trimmed its forecast for tablet growth in developed markets by half. In July, in an interview with Re/code, Hubert Joly, the CEO of Best Buy, said tablet sales are "crashing."

But Mr. Joly was bullish on PC sales, where Lenovo, the world's largest PC-maker, has a huge edge. The YOGA 3 Pro, a "convertible PC," will retail at Best Buy at the end of October for $1,349.

Earlier this month, Lenovo closed its acquisition of IBM's server unit, which will bring a number of enterprise marketers into Mr. Roman's fold; the company did not specify the total. The server business may boost Lenovo's desktop sales, which accounted for 29% of its revenue. Nearly half of its revenues come from "notebooks," convertible PCs and laptops like the YOGA 3 Pro. And around 15% comes from tablets and smartphones. Last quarter, Lenovo reported revenues of $10.4 billion, an 18% increase.

Soon, Lenovo will also finalize its purchase of Motorola, merging the world's fourth-largest smartphone vendor -- Lenovo holds 5%, per IDC -- with the fourth-largest smartphone vendor in the U.S. Analysts believe the acquisition will give Lenovo a smoother entrance into western marketers, a lift its Chinese peers lack.