Novel polyzirconosilane resin, prepared by Wurtz–Fittig copolymerization, was applied as a single source precursor for SiC–ZrC ceramics preparation. It could be rheologically much easily tailored catering to the precursor-infiltration–pyrolysis process in the production of ceramic composites. Polyzirconosilane resin could be thermally cured at 110–200 °C to form a solidified monolith and finally transformed at 1000–1400 °C to SiC–ZrC monoliths at a yield of around 65 wt%. The polyzirconosilane derived SiC–ZrC exhibited ultra-high thermo-oxidation resistance up to 1200 °C. The polyzirconosilane preceramic resin was an ideal candidate for SiC–ZrC multi-component ceramic under ultra-high temperature oxidation conditions.