jats:titleAjats:scbstract</jats:sc> </jats:title>jats:pThe resonant structure of the radiative decay jats:inline-formulajats:alternativesjats:tex-math$$ {\Lambda}_b^0\to {pK}^{-}\gamma $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> mml:msubsup mml:miΛ</mml:mi> mml:mib</mml:mi> mml:mn0</mml:mn> </mml:msubsup> mml:mo→</mml:mo> mml:msup mml:mipK</mml:mi> mml:mo−</mml:mo> </mml:msup> mml:miγ</mml:mi> </mml:math></jats:alternatives></jats:inline-formula> in the region of proton-kaon invariant-mass up to 2.5 GeV/jats:italicc</jats:italic>jats:sup2</jats:sup> 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 fbjats:supjats:italic−</jats:italic>1</jats:sup>. Results are given in terms of fit and interference fractions between the different components contributing to this final state. Only Λ resonances decaying to jats:italicpK</jats:italic>jats:supjats:italic−</jats:italic></jats:sup> are found to be relevant, where the largest contributions stem from the Λ(1520), Λ(1600), Λ(1800), and Λ(1890) states.</jats:p>