Angular distributions of the decay $B^0\to K^{⁎0}{\mu }^{+}{\mu }^{-}$ are studied using a sample of proton–proton collisions at $\sqrt{s}=8\text{TeV}$ collected with the CMS detector at the LHC, corresponding to an integrated luminosity of $20.5{\text{fb}}^{-1}$. An angular analysis is performed to determine the $P_1$ and $P_5^{\prime }$ parameters, where the $P_5^{\prime }$ parameter is of particular interest because of recent measurements that indicate a potential discrepancy with the standard model predictions. Based on a sample of 1397 signal events, the $P_1$ and $P_5^{\prime }$ parameters are determined as a function of the dimuon invariant mass squared. The measurements are in agreement with predictions based on the standard model.