Dark matter could be produced at the LHC if it interacts weakly with the Standard Model. The search for dark matter can be performed either directly, by looking for a signature of large missing transverse momentum coming from the dark matter candidates escaping the detector, or more indirectly by looking for the intermediate mediators which would weakly couple the dark matter particles to the Standard Model. A broad and systematic search program covering these various possibilities with the ATLAS detector is in place: the talk will review the latest results of these searches and show their complementarity.