To enhance the fire safety of historic buildings, developing fire-retardant coatings with integrated decoration, fire protection, ageing resistance and antibacterial performances is imperative. Here, a novel multifunctional transparent fire-retardant coating with fire protection, smoke suppression, antibacterial and anti-ageing functions was successfully fabricated using talc as a multifunctional synergist. Mechanical tests show that the multifunctional coating containing talc shows an improvement in pencil hardness and adhesion classification while keeping a high transparency. Moreover, adding talc is conductive to fabricate a physical barrier with super compactness and intumescence, which endows the coatings with excellent fire protection and smoke suppression functions. Especially, when the mass ratio of PPB to talc is 95:5, the obtained MTPPB3 coating retains a high-level transparency of 85.8%, accompanying with a 72.6% reduction in flame spread rating and a 57.0% reduction in smoke density rating compared to MTPPB0 without talc. TG analysis shows that the multifunctional coatings containing talc exhibit sharp enhancements in thermal stability and char yield, and MTPPB3 retains 32.7% residue at 800 °C. Meanwhile, the addition of talc results in high antibacterial rate against E. coli bacteria and durable flame-retardant and smoke suppression effects, and MTPPB3 shows an antibacterial rate of 99.0% against E. coli bacteria. This work provides a promising way to fabricate multifunctional transparent fire-retarded coatings with outstanding functions of decoration and fire protection.