Industrial agglomeration is a concentration phenomenon of economic activities in cities. In recent years, the geographic and functional structures of industries are constantly changing due to global industrialization and regional urbanization. Thus far, a scarcity of research has investigated spatial-functional organizations of sectoral industries in urbanized megaregions. By using points of interest (POIs) data collected in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), this paper seeks to portray the spatial extent of industrial agglomerations and to label their functional characteristics. A kernel density function is first applied to measure the spatial extent of industrial agglomerations. Next, we explore the industrial functions by implementing a semantic-based information retrieval to label the functional characteristics of industrial agglomerations via words that are tokenized from POI registered names. The empirical results suggest that the concentrations of industrial activities are strongly heterogeneous across different economic sectors, revealing that agglomerations across the GBA can provide a variety types of industrial products and services. Concerning manufacturing industries, the present analysis further confirms the existence of both specialization and diversification agglomerations along with far distinct spatial characteristics. This research supplements empirical evidence and provides novel insights into the geographical and functional organizations of economic activities regarding one of the largest urban megaregions in the world. The implications that are related to megaregional economic collaboration and development are discussed.