Identification of the origins of maritime-traded porcelain, though key to unravelling ancient production and trade dynamics, remains challenging. The authors present a pioneering micro-provenance analysis of Dehua-style porcelain from the late-twelfth-century Nanhai I shipwreck, recovered from the South China Sea. By pinpointing the origins of porcelain subtypes, including those bearing ink inscriptions, this study provides greater nuance in understanding spatial patterns of production and the impact of buyer/seller choice in maritime trade. The findings further highlight the effectiveness of portable x-ray fluorescence as a high-precision provenancing analysis and offer insights into porcelain production timelines in south-east China.