Lead　halide　perovskites　have　made　great　advance　in　direct　X-ray　detection,　however　the　presence　of　toxic　lead　and　the　requirement　of　high　working　voltages　severely　limit　their　applicability　and　operational　stability.　Thus,　exploring　＇green＇　lead-free　hybrid　perovskites　capable　of　detecting　X-rays　at　zero　bias　is　crucial　but　remains　toughly　challenging.　Here,　utilizing　chiral　R/S-1-phenylpropylamine　(R/S-PPA)　cations,　a　pair　of　0D　chiral-polar　perovskites,　(R/S-PPA)2BiI5　(1R/1S)　are　constructed.　Their　intrinsic　spontaneous　electric　polarization　induces　a　large　bulk　photovoltage　of　0.63 V,　which　acts　as　a　driving　force　to　separate　and　transport　photogenerated　carriers,　thus　endowing　them　with　the　capability　of　self-driven　detection.　Consequently,　self-driven　X-ray　detectors　with　a　low　detection　limit　of　270 nGy s−1　are　successfully　constructed　based　on　high-quality,　inch-sized　single　crystals　of　1R.　Notably,　they　show　suppressed　baseline　drift　under　the　self-driven　mode,　exhibiting　superior　operational　stability.　This　study　realizes　self-driven　X-ray　detection　in　a　single-phase　lead-free　hybrid　perovskite　by　exploiting　the　intrinsic　bulk　photovoltaic　effect,　which　sheds　light　on　future　explorations　of　lead-free　hybrid　perovskites　toward　＇green＇　self-driven　radiation　detectors　with　high　performance.　©　2023　Wiley-VCH　GmbH.