As the wave of oil and gas decommissioning activities begins across Thailand and Malaysia, issues related to the management of oil and gas decommissioning activities also begin to take shape, appearing in the form of disputes (Tanakasempipat 2019), schedule delays (Zainal Abidin and Mahasan 2019), scope creeps (Xu et al. 2019; Yap 2018), and cost overruns (Yusof, Ros and Omar 2018). One avenue to overcome the issues related to the management of oil and gas decommissioning activities in Thailand and Malaysia, is to enhance project managers’ understanding of the Thai and Malaysian oil and gas decommissioning landscape. Therefore, a research involving semi-structured interviews with 20 industrial representatives was conducted over the period of 2019 and 2020. This paper presents the findings from the research, detailing the regulatory structure and process, the supply chain and research capabilities, the operator's planning and execution behaviours for oil and gas decommissioning, and public stakeholders’ behaviours towards oil and gas decommissioning activities. The research findings will be presented in the form of a list of considerations, which project managers can utilize when managing future oil and gas decommissioning activities in Thailand and Malaysia. In addition, emergent research findings will also be summarized as a list recommendations for legislative and regulatory government bodies in order to further enhance the effectiveness of current regulatory arrangements.