High-spin states in the doubly magic $N=Z$ nucleus $^{56}\mathrm{Ni}$ have been investigated with three fusion-evaporation reaction experiments. New \ensuremath{\gamma}-ray transitions are added, and a confirmation of a previously suggested prompt proton decay from a rotational band in $^{56}\mathrm{Ni}$ into the ground state of $^{55}\mathrm{Co}$ is presented. The rotational bands in $^{56}\mathrm{Ni}$ are discussed within the framework of cranked Nilsson-Strutinsky calculations.