Person-centred care for individuals with complex needs often requires coordination across multiple providers, including hospitals, primary care, municipal services, and ambulance care. Yet such collaboration is frequently challenged by fragmented systems, unclear responsibilities, and differing organisational logics. This study draws on findings from a doctoral project exploring how person-centred care is enacted across organisational boundaries in Swedish healthcare. Using qualitative and systems-informed methods, the project examined collaboration in care transitions and discharge planning, focusing on older adults with complex needs. Findings show that person-centred care does not emerge automatically through formal structures or increased collaboration. Instead, it often arises in the “borderlands” between systems—through relational work, informal communication pathways, and adaptive strategies developed by front-line professionals. These everyday practices enable professionals to respond to patients’ needs in context, ensuring that the right care is delivered by the right actor at the right time. Key enablers of cross-boundary person-centred care include strong interprofessional relationships and trust, clear and flexible communication channels, shared responsibility and accountability for care transitions, and adaptive capacity to address system gaps. Conversely, rigid organisational structures, fragmented governance, and unclear mandates hinder seamless coordination. These findings challenge the assumption that “more collaboration” alone is the solution. Instead, they point to the importance of cultivating the conditions that make collaboration meaningful and effective from a person-centred perspective. This involves governance and leadership approaches that support relational continuity, flexibility, and shared accountability rather than relying solely on structural integration or digital solutions. By highlighting how person-centred care is achieved in practice, this work offers insights into how health and social care systems can better bridge organisational boundaries to meet the needs of individuals with complex needs.