His spokeswoman said: "Robbie Williams has today been admitted into a treatment centre in America for his dependency on prescription drugs. "There will be no further comment on this matter."
Robbie has entered a clinic in the US.
This is not the first time the star, who now lives in LA, has battled with drugs.
After he left Take That, he entered rehab for addiction to drink and drugs.
He recently cancelled the Asia leg of his Close Encounters world tour, citing stress and exhaustion as the reason.