AbstractFinancial resilience is founded on good financial planning behaviour. Contributing to theorisation efforts in this space, this study aims to develop a new theory that explains financial planning behaviour. Following an appraisal of theories, a systematic literature review of financial planning behaviour through the lens of the theory of planned behaviour (TPB) is conducted using the SPAR-4-SLR protocol. Thirty relevant articles indexed in Scopus and Web of Science were identified and retrieved from Google Scholar. The content of these articles was analysed using the antecedents, decisions, and outcomes (ADO) and theories, contexts, and methods (TCM) frameworks to obtain a fundamental grasp of financial planning behaviour. The results provide insights into how the financial planning behaviour of an individual can be understood and shaped by substituting the original components of the TPB with relevant concepts from behavioural finance, and thus, leading to the establishment of the theory of financial planning behaviour, which posits that (a) financial satisfaction (attitude), (b) financial socialisation (subjective norms), and (c) financial literacy, mental accounting, and financial cognition (perceived behavioural controls) directly affect (d) the intention to adopt and indirectly shape, (e) the actual adoption of financial planning behaviour, which could manifest in six forms (i.e. adoption of cash flow, tax, investment, risk, estate, and retirement planning). The study contributes to establishing the theory of financial planning behaviour, which is an original theory that explains how different concepts in behavioural finance could be synthesised to parsimoniously explain financial planning behaviour.