Developing a facile and versatile strategy to endow blood-contacting devices with surface in situ nitric oxide (NO) generation properties by catalytically decomposing endogenously existing S-nitrosothiols (RSNO) from blood is of immense scientific and engineering interest. However, most available strategies involve drawbacks of low efficiency, complex processes, and toxic chemicals. In this work, we report a facile method to deposit a NO-generating coating on a 316L stainless steel (SS) substrate through dopamine-mediated one-step assembly of CuII-dopamine (CuII-DA) coordination complexes. The chelation of CuII in the CuII-DA network endowed the coating with high in situ NO catalytic capacity by decomposing RSNO endogenously existing in blood. Of special importance is that this dopamine-mediated method possesses the merits of a simple preparation process, friendliness to the environment, high controllability of the CuII-DA surface chemistry, highly effective surface coating formation, and long-term and durable catalytic activity of NO. The continuous release of NO from the CuII-DA-coated 316L SS impressively improved its antithrombogenicity and selectively enhanced endothelial cell (EC) growth while inhibiting smooth muscle cell (SMC) proliferation.