Under hypoxic conditions during storage and transportation, potatoes are prone to developing blackheart, which severely degrades their quality and market value. In view of the limitations of existing studies, including the lack of measurements of optical properties of blackheart-affected tissues at wavelengths above 1000 nm and the neglect of differences among tissue regions, hindering an accurate representation of light transport behavior, this study employed a double integrating sphere system combined with the inverse adding-doubling algorithm to measure the absorption coefficient (μ_a) and reduced scattering coefficient (μ_s') of tissues with different blackheart severities over the 420–1650 nm spectral range. In addition, the Monte Carlo method was used to simulate light transport in multilayer blackheart-affected potato tissues. The results showed that μ_a increased significantly with increasing blackheart severity. At approximately 530 nm, the μ_a values of severely and mildly blackheart-affected tissues were 5.7 and 2.2 times that of healthy tissue, respectively. The μ_s' increased due to structural changes in tissues, with pronounced differences between the central and peripheral regions; the values in the peripheral region were generally 1.5–2.0 times those in the central region. Overall, the penetration depth of tissues followed the decreasing order of center > periphery > peel, with healthy tissue exhibiting greater penetration depth than blackheart-affected tissue. In the visible light region, the penetration depth of healthy tissue was 1.5 and 2.5 times that of mildly and severely blackheart-affected tissues, respectively, with more pronounced differences observed among different blackheart severities. Monte Carlo simulations of light transport in multilayered tissues combined with convolution analysis further indicated that light propagation in potato tissues was dominated by absorption. At 420 nm, attenuation was rapid and penetration was limited, whereas at 890 nm absorption was weaker, allowing deeper penetration and diffusion. Moreover, the diffuse reflectance response at 890 nm exhibited high sensitivity to lesions in peripheral tissues, demonstrating the strong potential of this wavelength for nondestructive detection of blackheart in potatoes. This study provides a theoretical basis for the nondestructive detection and grading of potato blackheart using spectroscopic techniques.