The aim of this study is to develop a simple method to grow an ultralong hydroxyapatite nanowire coating on a substrate. The ultralong hydroxyapatite nanowire coating on a glass substrate was synthesized by a one-step calcium oleate precursor solvothermal method. The formation process of the nanowire coating on the glass substrate was investigated, and the morphology, crystal phase and apatite-forming ability were studied. Moreover, the as-prepared hydroxyapatite nanowire coating exhibited excellent apatite-forming ability in simulated body fluid. The as-prepared ultralong hydroxyapatite nanowire coating has great potential for various biomedical applications.