Drawing on Bourdieu's concept of linguistic capital and Darvin and Norton's notion of investment, this study explores heritage language (HL) use among 1.5-generation Korean immigrants in the New Zealand workplace. The data were collected through interviews with heritage speakers of Korean working in diverse fields in Auckland. The majority of the participants had some degree of regular HL use at work, albeit limited to interactions with monolingual clients rather than with bilingual clients or colleagues. Some participants hesitated to use Korean in these situations because of their self-perceived imperfect HL skills and language anxiety. Moreover, although they perceived their HL as useful, they did not consider it a highly valuable form of linguistic capital in their professional lives. While they realized that HL proficiency would be valuable if they were to return to Korea for career-related purposes, none of them had plans to do so. Consequently, despite a stated interest in improving their HL proficiency, they did not actually invest in the HL. This study sheds light on the complex relationships between language ideologies, identity, and investment in HL learning in the context of diaspora, and offers pedagogical implications for HL education.