Using the CuII‐imidazole(Him) complex [Cu(Him)4Cl]Cl as the starting material, the imidazolate (im)‐ and azide‐bridged CuII coordination polymer [Cu3(Him)4(im)2(N3)4]n was successfully obtained. Single‐crystal X‐ray analysis revealed that it possesses an im‐bridged linear‐chain structure consisting of alternating dinuclear units with a symmetric end‐on azide‐bridged [Cu(μ1,1‐N3)2Cu]2+ core and mononuclear units. All of the Cu ions adopt a square pyramidal geometry with an azide at the Jahn–Teller elongated apical position. Some of the azides act as end‐to‐end interchain bridging ligands from the mononuclear unit to the nearest neighbouring dinuclear unit of the adjacent chain forming a two‐dimensional network. Temperature‐variable magnetic susceptibility measurements showed that it exhibits one‐dimensional ferrimagnetic‐like behaviour, which can be ascribed to two types of exchange couplings with opposite signs, namely a weak ferromagnetic coupling through the end‐on azide bridges within the dinuclear units and a stronger antiferromagnetic coupling through the im bridges between the di‐ and the mononuclear units.