Figures released Monday by the state Division of Gaming Enforcement show the city's 12 casinos took in $212.3 million.
The decline was helped by the fact that 2012 was a leap year in which February had 29 days, compared with the usual 28 this year.
Revel, the city's newest casino which will file a Chapter 11 bankruptcy petition this month, saw revenue rise to $9 million, up from $7.9 million in January.
February is traditionally one of the slowest months of the year in Atlantic City.
The state is hoping its legalization of Internet gambling, which could take effect by the end of this year, will provide new revenue and end the decline.