Ground-state and low-energy excitations of the quasi-one-dimensional antiferromagnet CuSe2O5 where finite interchain interactions promote long-range antiferromagnetic order below T-N = 17 K, were experimentally studied using bulk magnetization, neutron diffraction, muon spin relaxation, and antiferromagnetic resonance measurements. The derived spin-canted structure is characterized by the magnetic propagation vector k = (1,0,0) and the reduced magnetic moment m = [0.13(7), 0.50(1), 0.00(8)] mu(B). The values of the magnetic anisotropies determined from the field and angular dependencies of the antiferromagnetic resonance comply well with a previous electron paramagnetic resonance study and correctly account for the observed magnetic ground state and spin-flop transition. DOI: 10.1103/PhysRevB.87.104413