Linda Yaccarino, NBCUniversal’s promoting chief, was making ready to interview Elon Musk, Twitter’s proprietor, onstage at a convention final month when she acquired an e-mail from a peer within the promoting business.

Rob Norman, a former govt on the advert big WPP, needed to know if Ms. Yaccarino had seen the op-ed he wrote after Mr. Musk bought Twitter final 12 months. Mr. Norman’s column mentioned the tech billionaire’s amplification of misinformation on Twitter and its chilling impact on advertisers.

Ms. Yaccarino mentioned that she had and that she deliberate to lift such considerations, Mr. Norman mentioned. But the primary focus of her discuss with Mr. Musk could be on one thing else: His efforts to revamp the social community into “Twitter 2.0.”

Now Ms. Yaccarino is ready to grow to be the face of Twitter 2.0. Mr. Musk mentioned on Friday that he had chosen Ms. Yaccarino, 60, to grow to be the corporate’s chief govt. Hours earlier, NBCUniversal introduced that Ms. Yaccarino was leaving, efficient instantly.

“I am excited to welcome Linda Yaccarino as the new C.E.O. of Twitter,” Mr. Musk tweeted. He mentioned she would primarily deal with enterprise operations whereas he would proceed engaged on product design and expertise.

In selecting Ms. Yaccarino, Mr. Musk is signaling what his precedence is at Twitter: its promoting enterprise, quite than social media know-how. Ms. Yaccarino has been one in every of Madison Avenue’s energy brokers for many years. And Twitter, which makes the majority of its income from advertisements, has struggled to broaden that enterprise, particularly after Mr. Musk spooked advertisers final 12 months.

“Linda’s a force,” mentioned Joe Marchese, the previous head of advert gross sales on the Fox Networks Group, who has recognized Ms. Yaccarino for no less than a decade. “She has one of the biggest jobs in advertising, and the ad market is as hard as it’s ever been.”

Yet Ms. Yaccarino should do greater than deal with Twitter’s promoting woes. The firm, which relies in San Francisco, has been severely slimmed down since Mr. Musk slashed 75 % of its work power and has grappled with gaps in experience and technical glitches. Twitter can be weighed down by $13 billion in debt that it took on to allow Mr. Musk to purchase the corporate.

Most considerably, Ms. Yaccarino must cope with a mercurial and unpredictable boss in Mr. Musk. The 51-year-old billionaire has a monitor report of firing executives who don’t obtain his objectives. He generally tweets news about his varied firms, which additionally embrace the electrical carmaker Tesla, with out warning. And as Twitter’s proprietor, Mr. Musk retains absolute energy on the firm.

Mr. Musk already upended Ms. Yaccarino’s rigorously laid plans when he tweeted on Thursday that he had chosen a brand new Twitter chief, although he didn’t establish her. Ms. Yaccarino, who was in back-to-back rehearsals for NBC’s annual pitch to main advertisers when the tweet went out, hadn’t knowledgeable a lot of her fellow executives that she was planning to depart, 4 folks with information of the matter mentioned.

Lou Paskalis, a longtime advert govt and buddy of Ms. Yaccarino, likened her transfer to Twitter to taking a “step into the lion’s mouth.”

“With her stature in the industry as probably one of the most beloved and trusted people on the revenue side, I question why she would subject herself to that kind of potential reputational risk,” he mentioned.

Mr. Musk and Ms. Yaccarino could also be betting that there’s loads of upside with Twitter 2.0. Mr. Musk has laid out formidable plans for the corporate, telling staff that it might be price $250 billion sooner or later and that the platform could be an “everything app,” with options like funds. (He just lately mentioned that Twitter is worth $20 billion, down from the $44 billion he paid for it.)

Ms. Yaccarino has already been engaged on her priorities at Twitter. One one that has spoken together with her in latest days mentioned that she is targeted on repairing the corporate’s relationship with Madison Avenue and wooing media firms again to the platform, doubtlessly with partnership offers.

And she and Mr. Musk seem aligned on political points — comparable to a extra permissive strategy towards speech on Twitter — which are central to his imaginative and prescient for the platform, two folks acquainted with her views mentioned. She is a conservative and a critic of so-called woke discourse, a time period utilized by conservatives to explain parts of left-wing social progressivism they view as censorious, they mentioned.

Former President Donald J. Trump twice appointed Ms. Yaccarino to two-year phrases on the President’s Council on Sports, Fitness and Nutrition, the place she joined would-be Republican politicians comparable to Mehmet Oz, the superstar doctor.

Ms. Yaccarino, who didn’t return requests for remark, grew up with working-class Italian parents in Long Island, New York, together with a father who was a police officer. She attended Catholic college. After graduating from Pennsylvania State University in 1985 with a telecommunications diploma, she spent practically 20 years at Turner Entertainment, turning into chief working officer of promoting gross sales, advertising and marketing and acquisitions earlier than leaving for NBCUniversal in 2011.

At Turner and NBCUniversal, Ms. Yaccarino — who has been mentioned to barter like a “velvet hammer” — made a reputation for herself by serving to conventional tv hold its ground in promoting within the period of Facebook and Google. Each 12 months, she strode onstage at Radio City Music Hall for the upfront displays, the glitzy showcases utilized by tv networks to woo Madison Avenue, to influence entrepreneurs to pay a hefty premium over social media charges to promote on reveals like “This Is Us” and “Saturday Night Live.”

But whereas Ms. Yaccarino has spent years defending TV advert {dollars} from tech firms and been a fierce critic of Facebook and YouTube, she has additionally struck partnerships with apps like Snapchat and TikTok and digital shops like BuzzFeed.

Outside work, Ms. Yaccarino turned closely concerned in initiatives together with the World Economic Forum’s Taskforce on Future of Work, which she heads. She was additionally a chair on the board of the Ad Council, a nonprofit group, and helped the group elevate $60 million in three months early within the pandemic to assist counter vaccine hesitancy, making non-public calls, sending notes and “working every lever that she had,” mentioned Lisa Sherman, the council’s chief govt.

It’s unclear when Ms. Yaccarino met Mr. Musk, however they publicly interacted onstage on the media convention final month on the ritzy Fontainebleau Miami Beach lodge in Florida. Ms. Yaccarino had beforehand expressed admiration for Twitter, calling the platform “the single, No. 1 biggest” content material distribution companion for NBCUniversal at an ad industry event quickly after Mr. Musk took over the corporate. At the time, she added that she didn’t plan to “bet against him” and that she believed he might “learn advertising.”

“I think we can teach him,” she mentioned.

This week, Ms. Yaccarino was in attendance when Mr. Musk spoke at an promoting convention in California’s Napa Valley hosted by WPP, three folks acquainted with the occasion mentioned.

Ms. Yaccarino could be a uncommon feminine chief govt in expertise, as high executives like Meta’s Sheryl Sandberg and YouTube’s Susan Wojcicki have just lately left their roles. Throughout her profession, Ms. Yaccarino has usually mentioned that she has been the one lady on the desk and has described incidents of bias, such because the time a male supervisor complained in an in any other case flattering efficiency evaluate about her aggressiveness: “I only wish she would stop using her high heels as a weapon.”

While Ms. Yaccarino is lively on Twitter, her habits are sedate compared to Mr. Musk’s, although in latest weeks, she has appreciated dozens of posts by and about him.

Still, the variations between Mr. Musk and Ms. Yaccarino have been clear final month on the media convention in Miami. A refined Ms. Yaccarino got here with ready feedback. An unshaven Mr. Musk spent a couple of moments wrangling his toddler son, X Æ A-12, earlier than becoming a member of her and providing generally halting solutions to her questions.

Ms. Yaccarino returned repeatedly to worries that her business colleagues have voiced since Mr. Musk took management of Twitter, emphasizing a number of instances that the viewers of advert executives was essential to the corporate’s monetary success.

Mr. Musk mentioned that “there’s legitimate concerns that advertisers have that I want to hear.” He recounted a criticism he had heard from David Zaslav, the chief govt of Warner Bros. Discovery, who was pissed off that he was unable to put advertisements for “White Lotus,” the hit HBO present, subsequent to discussions of “White Lotus” on Twitter.

The challenge has since been fastened, Mr. Musk mentioned.

Ms. Yaccarino answered: “So it’s a new beginning.”

John Koblin contributed reporting from New York.