Andrew Harrer/Bloomberg News Arianna Huffington said that as she began talking to Tim Armstrong of AOL, “it was really amazing how aligned our visions were.”

The Huffington Post, which has grown from its small but splashy debut in 2005 into one of the Web’s most popular news sites, has agreed to sell itself to AOL, Jeremy W. Peters and Verne G. Kopytoff report in The New York Times on Monday.

Under the terms of the deal, AOL will pay $315 million — $300 million in cash and the rest in stock.

Andrew Harrer/Bloomberg News On Sunday, Tim Armstrong said the deal fit “right into our strategy.”

The deal is AOL’s biggest since separating from Time Warner in 2009, and showcases the company’s intent to focus on original content. (In September, AOL bought TechCrunch, the influential technology blog founded by Michael Arrington.)

But it also represents a major media move by The Huffington Post’s co-founder, Arianna Huffington.

More from The Times:

Arianna Huffington, the cable talk show pundit, author and doyenne of the political left, will take control of all of AOL’s editorial content as president and editor in chief of a newly created Huffington Post Media Group. The arrangement will give her oversight not only of AOL’s national, local and financial news operations, but also of the company’s other media enterprises like MapQuest and Moviefone. By handing so much control over to Ms. Huffington and making her a public face of the company, AOL, which has been seen as apolitical, risks losing its nonpartisan image. Ms. Huffington said her politics would have no bearing on how she ran the new business. The deal has the potential to create an enterprise that could reach more than 100 million visitors in the United States each month. For The Huffington Post, which began as a liberal blog with a small staff but now draws some 25 million visitors every month, the sale represents an opportunity to reach new audiences. For AOL, which has been looking for ways to bring in new revenue as its dial-up Internet access business declines, the millions of Huffington Post readers represent millions in potential advertising dollars. “This is a statement that the company is making investments, and in this case a bold investment, that fits right into our strategy,” Mr. Armstrong said in an interview on Sunday. “I think this is going to be a situation where 1 plus 1 equals 11.” Ms. Huffington and Mr. Armstrong began discussing the possibility of a sale only last month. They came to know each other well after they both attended a media conference in November and quickly discovered, as Ms. Huffington put it, “we were practically finishing each other’s sentences.” She added: “It was really amazing how aligned our visions were.”

Ms. Huffington shares her thoughts — naturally — on her own site. Here is an excerpt from her post: