We present a comprehensive study of high-energy double logarithms in inclusive DIS. They appear parametrically as α n s ln 2n−k x at the n-th order in perturbation theory in the splitting functions for the parton evolution and the coefficient functions for the hard scattering process, and represent the leading corrections at small x in the flavour non-singlet case. We perform their resummation, in terms of modified Bessel functions, to all orders in full QCD up to NNLL accuracy, and partly to N 3 LL and beyond in the large-n c limit, and provide fixed-order expansions up to five loops. In the flavour-singlet sector, where these double logarithms are sub-dominant at small x compared to single-logarithmic α n s x −1 ln n−k x BFKL contributions, we construct fixed-order expansions up to five loops at NNLL accuracy in full QCD. The results elucidate the analytic small-x structure underlying inclusive DIS results in fixed-order perturbation theory and provide important information for present and future numerical and analytic calculations of these quantities. c 83997239 1944 − 2253859 81 ζ 2 + 13220 9 ζ 3 + 48070 3 ζ 4 + 64 ζ 3 ζ 2 − 4312 3 ζ 5 + 176 ζ 2 3 − 1444 ζ 6 + n f C F n 3 c − 5138330 243 + 267860 27 ζ 2 − 4336 3 ζ 3 − 28432 9 ζ 4 + 128 ζ 3 ζ 2 + 1504 3 ζ 5 − 64 ζ 2 3 − 248 ζ 6 + n 2 f C F n 2 c 760669 243 − 9076 9 ζ 2 + 2000 9 ζ 3 + 1408 9 ζ 4 + n 3 f C F n c − 12826 81