Measurements of dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$ using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of $2.9\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. The results are compared to predictions from perturbative QCD calculations and various Monte Carlo event generators. The dijet azimuthal distributions are found to be sensitive to initial-state gluon radiation.