© 2018 American Physical Society. The only unequivocal known criterion for single-parameter scaling Anderson localization relies on the knowledge of the full conductance statistics. To date, theoretical studies have been restricted to model systems with symmetric scatterers, hence lacking universality. We present an in-depth statistical study of conductance distributions P(g), in disordered 'micrometer-long' carbon nanotubes using first principles simulations. In perfect agreement with the Dorokov-Mello-Pereyra-Kumar scaling equation, the computed P(g) exhibits a nontrivial, non-Gaussian, crossover to Anderson localization which could be directly compared with experiments.