A patterned reduced graphene oxide/silver nanoparticles assembled on Al sheet was facilely fabricated using layer-by-layer assembly combined with thermal reduction. The plug-and-play composite sheet shows stable and reproducible performance for SERS detection and catalytic degradation for a toxic malachite green. • A patterned RGO and Ag nanoparticles were facilely assembled on Al sheet. • The sheet was highly active for detection and degradation towards malachite green. • The cost-effective sheet with double functions was stable and reproducible. • The patterned RGO was very significant to the high performance of the sheet. In this work, a patterned reduced graphene oxide (RGO)/silver nanoparticles on Al sheet was prepared using layer-by-layer assembly technique. The morphology, structure and composition of the Al/RGO/Ag were investigated using SEM, XRD and XPS. It showed that there existed a strong interaction among Al, the patterned reduced graphene oxide and Ag nanoparticles in the Al/RGO/Ag sheet, which made the patterned Al/RGO/Ag sheet be as a sensitive SERS material for rapidly monitoring trace malachite green with good reproducibility and high stability. Also, the plug and play Al/RGO/Ag sheet exhibited high and stable catalytic degradation activity for malachite green. The constructed bifunctional sheet will provide some references for designing those materials used in detection and degradation of contaminants in wastewater.