Advertising will appear in Facebook news feeds from early 2012 alongside updates from friends and applications.
Until now the adverts have mostly been restricted to the right-hand side of the page.
However the social network has announced that from next year ads will also take the form of news stories and 'standard' updates.
The new "Sponsored Stories" will appear when a person "likes" a brand. The ad box will then be pushed to that user's friends and contacts.
"Our goal is to do this thoughtfully and slowly," Facebook said. "We hope to show people no more than one Sponsored Story in their news feeds per day and the story will be clearly labelled as sponsored."
However a previous attempt to integrate ads with the central news feed was abandoned in 2008 because of the negative reaction by users.
The change could help advertisers reach customers in a more direct way, and could drive up Facebook's revenues.
The Financial Times said that the network was under pressure to make more money, hence the change.
"Facebook is under a lot of pressure to make money right now," Rebecca Lieb, an analyst with the Altimeter Group, told the newspaper. "Users have to understand the value exchange of getting what you pay for."