Recent entrepreneurship research has suggested that opportunity development takes place as entrepreneurs move through the stages of intention formation, opportunity recognition, opportunity evaluation, and opportunity implementation. One major issue with this staged approach is that it is unclear how individuals make sense of such an entrepreneurial opportunity. Using a sensemaking approach (variation-selection-retention or VSR), this thesis develops a theoretical framework aiming to understand the cognitive processing of the transition between entrepreneurial opportunity and entrepreneurial action. Here, entrepreneurial opportunity is further developed once an entrepreneurial action has been realised. The theoretical framework is subsequently employed to analyse the role of home-country culture on decision-making leading to action, which ultimately develops opportunity. Using interpretive phenomenological analysis (IPA), this study provides a detailed examination of the lived experience of nine (9) Vietnamese entrepreneurs in the UK. IPA is suitable for answering the research question: How do Vietnamese entrepreneurs develop opportunity through their cultural lens during immigrant entrepreneurship? Four cultural values of Vietnamese neo-Confucianism are identified in the literature review: fragmented, uncritical, suspicion-oriented, and stability-seeking (or FUSS). The findings propose that each cultural value dominantly affects a particular VSR stage driving entrepreneurial action. This research contributes to the literature and practice by (1) confirming action as resembling opportunity development regardless of the stage of the entrepreneurial process (Dimov, 2007), (2) promoting the link between culture and entrepreneurship viewed under the cognition-behaviour perspective (Kerr & Coviello, 2020), and (3) supporting a shift in entrepreneurship research to the context of less accessible and less visible ethnic minority groups such as the Vietnamese community in London (Bagwell, 2018).