The differential cross-section of prompt inclusive production of long-lived charged particles in proton-proton collisions is measured using a data sample recorded by the LHCb experiment at a centre-of-mass energy of √s = 13 TeV. The data sample, col- lected with an unbiased trigger, corresponds to an integrated luminosity of 5.4 nb−1. The differential cross-section is measured as a function of transverse momentum and pseudora- pidity in the ranges pT ∈ [80, 10 000) MeV/c and η ∈ [2.0, 4.8) and is determined separately for positively and negatively charged particles. The results are compared with predictions from various hadronic-interaction models.