Rick Ross -- 24-Hour ARMED SECURITY After Drive-By Shooting

Rick Ross is fighting fire with firepower ... 'cause the rap mogul just hired 24-hour ARMED personal security to watch his back in the wake of Monday's drive-by shooting ... TMZ has learned.

Ross -- aka Ricky Rozay -- was already using armed bodyguards for protection at major events like concerts and public appearances ... but now he's decided he wants a full-time security detail.

Ross was targeted in a drive-by shooting in Florida early Monday morning ... when a car pulled up next to his Rolls-Royce and opened fire. Ross lost control of the vehicle during the incident and crashed into an apartment building.

Sources close to Ross tell TMZ ... the rapper had been getting threats for a while ... but he wasn't too concerned. But we're told Ross considers the shooting to be an "eye-opener" and will do whatever it takes to keep himself safe.