Despite increasingly dynamic and uncertain employment contexts, existing research remains largely grounded in traditional employment frameworks, offering limited insight into the strategic role of job search success in fostering career sustainability and informing organizational talent management. This paper addresses this gap by integrating control theory with the boundaryless career perspective to propose a unified theoretical framework of job search success, encompassing three critical objectives: securing employment, facilitating organizational transitions and enhancing career sustainability. A six-dimensional measure of job search success was developed and validated through four studies, including qualitative model development, content validation, cross-cultural assessment, and a nine-month time-lagged survey. This job search success model integrates established dimensions (e.g., Perceived Quantity, Efficiency, Person-Environment Fit, and Reward Competitiveness) with two novel dimensions (Personal Distinctiveness and Perceived Variety) that are particularly relevant in boundaryless career contexts. The six-factor construct generalizes across cultures and explains significant incremental variance in key work and career outcomes that are critical not only for job seekers' organizational transitions (e.g., job satisfaction, salary growth) but also for their long-term career sustainability in both internal (e.g., organization-based self-esteem) and external (e.g., external employability) labor markets. Notably, Personal Distinctiveness emerges as a critical driver of organization-based self-esteem, and Perceived Variety is pivotal for external employability. Our study contributes a contemporary, theory-grounded framework for job search success and lays the foundation for future research on sustainable career management and talent management in boundaryless career contexts.