The decay is reconstructed in pp collision data, corresponding to 2 fb−1 of integrated luminosity, collected by the LHCb experiment at a centre-of-mass energy of TeV. The product of the Z production cross-section and the branching fraction is measured for candidates in the fiducial region defined by two particle-level b-quark jets with pseudorapidities in the range , with transverse momenta GeV and dijet invariant mass in the range GeV. From a signal yield of events, where the uncertainty is statistical, a production cross-section times branching fraction of pb is obtained, where the first uncertainty is statistical and the second systematic. The measured significance of the signal yield is 6.0 standard deviations. This measurement represents the first observation of the production in the forward region of pp collisions.