Starting as a journalist, she went from creating magazines for Rupert Murdoch to running ABC Entertainment for Walt Disney to heading Martha Stewart Living Omnimedia –then led online fashion retailer Gilt Groupe.

So Lyne’s arrival today at AOL , as CEO of its Brand Group, comes as a surprise…and not.

“This represents a convergence of all that came before–print, video, technology and brand-building,” she says, pinpointing the logic of her new gig. “It’s as close as I can imagine to having it all.”

An AOL director since 2009, Lyne says that before Christmas, AOL chief Tim Armstrong asked her if she would consider stepping off the board and into a key position inside the company. Over a 10-day holiday with friends in Burma, Lyne weighed Armstrong’s offer—and considered why she shouldn’t accept it. Having moved from Gilt CEO to chairman to vice-chairman, she envisioned her future: “I thought, I’m going to start investing and advising, and it’s going to be a wonderful free existence.”

Then Lyne thought about why she should take the job. Gilt had just brought in a new CEO–board member Michele Peluso from Citigroup –and was on track to go public in the coming year. While the “wonderful free existence” tempted her, Lyne, at 62, wasn’t ready to hang it up. In fact, she decided, the prospect of “putting my head down and working 12 hours a day” sounded fun.

So here she is on her first day at AOL. As chief of the Brand Group, Lyne is overseeing the company’s content assets including Tech Crunch, Engadget and Patch, a collection of local-news sites. The one site not in Lyne’s charge: the Huffington Post. Arianna Huffington and Lyne, longtime friends, rank as equals and both report to Armstrong.

Perpetually drawn to “where the heat is,” Lyne sees in AOL the chance to help Armstrong, who came from Google in 2009, create “the media company of the future,” she says. “I really sense an attitude shift around content–from commodity status to critical differentiator.” As for Armstrong, she adds, “I adore Tim. After he acquired the Huffington Post and Tech Crunch, all the naysayers thought he would destroy them or lose control of them. Instead, they’ve flourished and grown in value.”

Indeed, Armstrong has AOL growing again for the first time in eight years. And the stock, at $36, has doubled in the past year.

Says Armstrong about Lyne: “My job is to bring in the world’s most powerful brand people, and Susan is one of them.” And it’s no coincidence that she adds to his stable of C-suite women. “The Internet was designed primarily by men, but at least half of the users are women,” Armstrong says. “To design products and services with women in leadership positions is one of the best opportunities in the world.”