Internationally operating professionals in China study business English to develop their language proficiency and transcultural communicative competence. While a variety of business English textbooks are on the market and are used in China, their conceptualizations of culture tend to be nation-based, static, and predictable -- views of culture that have been increasingly problematised in the field of second language teaching and learning. This investigation drew on a research-informed conceptualisation of linguacultural competence that incorporates three theoretical lenses: Business English as a Lingua Franca (BELF), linguaculture, and genre. Competencies identified in the research literature were cross-checked with empirical data from active job-experienced business professionals via semi-structured interviews and questionnaires. These competencies were then used to examine how one popular business English textbook, "Market Leader Intermediate," fares in developing linguacultural competence. The results revealed that while the textbook includes opportunities to develop several necessary competencies, many others are not addressed. Further, expressions of culture in the textbook are often simplistic or limited. These findings can inform textbook adaptations and development for effectively inculcating linguacultural competence in internationally functioning professional communicators.