Supersymmetry (SUSY) is one of the most relevant scenarios of new physics searched for by the ATLAS experiment at the CERN Large Hadron Collider (LHC). In this paper the principal search strategies employed by ATLAS are outlined and the most recent results for analyses targeting SUSY discovery are presented. A wide range of signatures are covered motivated by various theoretical scenarios and topologies: strong production, third-generation fermions, electroweak production and $R$-parity violation among others. Most results are based on $\sim13 -18~{\rm fb}^{-1}$ of data recorded in 2015 $-$ 2016 at $\sqrt{s} = 13~{\rm TeV}$ centre-of-mass energy by the ATLAS experiment at the LHC.