Says its making roughly $500,000 a day from mobile ads.
The stat came in the company's Q2 financials, which showed Facebook meeting expectations with revenues of $1.2bn and a net loss of $157m.
Despite this, shares fell 11 per cent to $24. That's almost half their launch price.
Of course, mobile usage is still the driver of much of Facebook's growth. Mobile MAUs were 543 million as of June 30th, 2012, an increase of 67 per cent year on year.
This represents around six in ten of the firm's 955m total monthly active users, which was up 29 per cent year-on-year.
In the past, Facebook has conceded the difficulty of making money from mobile – a platform on which advertising can appear intrusive. The firm says 84 per cent of its total revenue comes from advertising at present.
Facebook has introduced 'Sponsored Stories' in the mobile News Feed, and bought Instagram to beef up its mobile presence. It also purchased Face.com, whose facial recognition software may improve its ability to track and monetise individual users, privacy permitting.
And Facebook CEO Mark Zuckerberg is insistent that the firm is succeeding in making mobile a profit centre.
He told investors: “By the end of June, Sponsored Stories in News Feed was at a run rate of over $1 million per day in revenue, and about half of that is coming from mobile.