A combination of measurements of associated production of a Standard Model Higgs boson with an electroweak gauge boson, or , is presented, targeting Higgs boson decays to bottom quarks and or boson decays to leptons. The measurements that enter the combination were optimised for different regimes of the transverse momentum of the or boson and reconstruct the Higgs boson candidate as two individual jets or a single large-radius jet. The measurements use proton-proton collision data produced by the Large Hadron Collider at a centre-of-mass energy of ~TeV and collected with the ATLAS experiment between 2015 and 2018. The data set corresponds to an integrated luminosity of ~fb. Cross-sections are measured in fiducial volumes as defined by the simplified template cross-section framework. The cross-sections are extracted in several categories of transverse momentum of the and bosons. The measurements are compatible with the Standard Model expectation, with uncertainties between 30\% and 300\%. Limits are subsequently set on the parameters of an effective Lagrangian sensitive to modifications of the associated production of a Higgs boson. The combination provides more stringent limits than the individual analyses on parameters that depend strongly on the electroweak gauge boson's momentum.