Facebook earned 64 million US dollars (£40.7 million) in the October-December period, down from 360 million US dollars (£229 million) a year earlier when it was still a privately held company.
Revenue rose 40% to 1.59 billion US dollars (£1.01 billion) from 1.13 billion US dollars (£718.8 million).
Excluding special items, mainly related to stock compensation expenses, Facebook, which is based in Menlo Park, California, earned 17 cents (11p) per share in the latest quarter.
Analysts polled by FactSet expected lower adjusted earnings of 15 cents (9.5p) per share on revenue of 1.51 billion US dollars (£960.5 million).
Facebook said it generated 23% of advertising revenue from mobile, up from 14% in the third quarter.
Facebook shares were down 4.3% to 29.91 US dollars (£19.03) after hours.