High‐field superconductors are characterized by a spin splitting of the density of states, giving rise to spin transport phenomena. This includes spin‐polarized tunneling, spin‐dependent thermoelectric effects, long‐range quasiparticle spin transport, and spin‐dependent coupling of supercurrents and quasiparticles. This review gives a brief overview of the theory background, recent experimental progress in the field, and an outlook on open problems and possible applications.