Rapid and precise cancer subtype discrimination is essential for personalized oncology. Conventional diagnostic methods often lack sufficient accuracy and speed. Here, we introduce a multichannel fluorescence-encoded nanosystem based on erythrocyte-coated polydopamine nanoparticles (PDA@EM), functionalized with multiple resurfaced fluorescent proteins. The fluorescence of these proteins is initially quenched by PDA@EM and restored upon cell addition. This multichannel fluorescence-encoded nanosystem enables highly sensitive "turn-on" fluorescence profiling of cancer cells within 30 min, achieving 100% accuracy in distinguishing various proteins and classifying a wide range of cancer cell lines, including subtypes of oral squamous cell carcinoma (OSCC). Notably, it offers rapid, label-free diagnostics of OSCC malignancy from clinical samples postsurgery. This capability was validated through histopathological and proteomic analyses, which identified protein signatures associated with tumor progression and immune suppression. Overall, our multichannel nanosensor represents an advanced molecular diagnostics platform, paving the way for personalized cancer treatment in clinical oncology.