These proceedings present the first search for CP-violation in the top-Yukawa coupling using $t\bar{t}H$ and $tH$ production modes in the diphoton decay channel ($H\to\gamma\gamma$).
The analysis is based on the 139 fb$^{-1}$ of proton-proton collision data at center-of-mass energy $\sqrt{s}$=13 TeV recorded with the ATLAS detector at the Large Hadron Collider.
Two separate set of selections are introduced to capture the full hadronic and leptonic decay of the $t\bar{t}$ system each.
This search is performed using a simultaneous fit to the diphoton invariant mass distribution in analysis categories defined to enhance signal over continuum background and also to separate the CP-even and CP-odd signal hypotheses.