A bstract The resonant structure of the radiative decay $$ {\Lambda}_b^0\to {pK}^{-}\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>b</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>pK</mml:mi> <mml:mo>−</mml:mo> </mml:msup> <mml:mi>γ</mml:mi> </mml:math> in the region of proton-kaon invariant-mass up to 2.5 GeV/ c 2 is studied using proton-proton collision data recorded at centre-of-mass energies of 7, 8, and 13 TeV collected with the LHCb detector, corresponding to a total integrated luminosity of 9 fb − 1 . Results are given in terms of fit and interference fractions between the different components contributing to this final state. Only Λ resonances decaying to pK − are found to be relevant, where the largest contributions stem from the Λ(1520), Λ(1600), Λ(1800), and Λ(1890) states.