Master-Planned Residential Estate (MPRE) is an integrated housing development form in Australia. MPREs are aimed to build a sense of place attachment and community via the provision of environmental and social infrastructure. Neighbourhood parks are regarded as a significant built environmental factor linked to residents’ place attachment and well-being in the literature. Understanding place attachment is crucial for promoting residents’ well-being in neighbourhoods and enhancing the attractiveness of real estates in the housing market. However, we know little about how place attachment is facilitated for park users in neighbourhoods. The psychological process of place attachment in MPREs is unclear in the literature, with a particular lack of qualitative studies in this area. This study explored the psychological process of place attachment and its associations with neighbourhood parks in MPREs in Sydney via a qualitative case study. Semi-structured interviews were conducted with 16 residents residing in two selected MPREs in Sydney during the COVID-19 pandemic in 2022. Interviews found three themes and several subthemes regarding the process of place attachment for park users in MPREs: affect (emotional bonds), behaviour (place-related fulfilment of needs, place-related social bonds, and community participation), and cognition (membership of the community, place-related memory, and cultural significance). This study contributes to understanding place attachment and human-environment relations in sustainable neighbourhoods by adding new items into place attachment models from the perspective of MPREs in Sydney. It provides valuable qualitative evidence gathered during the COVID-19 pandemic. The findings furnish empirical insights for policymakers, developers, and urban planners involved in sustainable neighbourhoods’ development and housing management in Sydney and global regions.