As precision medicine increasingly reveals the biological diversity among individuals, the demand for higher-throughput screening techniques, particularly suspension array technologies capable of more multiplexing from smaller samples in a single run, is intensifying. However, advancements in the multiplexing capability of current suspension platforms have lagged with limited alleviation, necessitating breakthroughs for innovative solutions that enable larger-scale measurements. Here, we introduce such a breakthrough with a novel mass-cytometric barcode engineering by metal nanoparticle-based "Lego Brick"-like self-assembly for high-throughput barcode design and capacity amplification. The suspension array capacity can be expanded to over 20,500 unique barcodes by flexibly assembling just 10 types of barcoding units (metal nanoparticles) onto the surface of the barcoding center (magnetic spheres) through a universal biotin-streptavidin binding template, significantly enhancing both throughput and versatility. Further multiplexed immunoassay, termed MassMAP, demonstrates high-throughput profiling of cancer biomarkers, highlighting the revolutionary potential of Lego Brick self-assembly in massive cytometric screening for higher-throughput applications.