Recently, antimicrobial surface coatings have emerged as an effective strategy to mitigate microbial contamination and disease transmission. The application of cuprous (I) oxide (Cu2O) and copper (II) pyrithione (CPT) in antimicrobial surfaces faces several challenges such as deep color, weak stability, limited functionality, and poor dispersion in coatings. These challenges complicate the design of novel copper-based antimicrobial agents. In this study, high-purity CPT was synthesized innovatively using Cu2O as a copper source, differing from traditional methods. Following this approach, diatomaceous earth/cuprous oxide/copper pyrithione (DME/Cu2O/CPT) composites with enhanced antimicrobial activity and a lighter color than Cu2O and CPT were prepared by adjusting the SPT dosage. Notably, in DME/Cu2O/CPT composites, Cu2O existed as nanoscale fragments adhering to the surfaces of CPT. Furthermore, coatings made from composites and latex paint exhibited a lighter color difference, higher stability, and exceptional antimicrobial activity against pathogens such as S. aureus, E. coli, P. aeruginosa, C. albicans, and human enterovirus 71. The DME/Cu2O/CPT composites displayed high, stable, and broad-spectrum antimicrobial efficacy, attributing to the synergistic enhancement effects of released Cu+ and Cu2+. Consequently, this study introduced a simple and scalable method for preparing DME/Cu2O/CPT composites, serving as a coating additive with broad-spectrum antimicrobial activity and long-term stability for various solid surfaces.