Increasing career and life development hope (CLDH) is critical for the career and life pursuits of non-engaged youths (NEY) who face various disadvantages in the school-to-work transition, especially considering current challenging labor market conditions and the impacts of the pandemic. Nevertheless, research that explores the assessment of CLDH among NEY is scarce. To address this gap, this study aimed to develop and validate a CLDH measurement instrument. A total of 1998 NEY aged 13–29 years in Hong Kong participated in our study. Exploratory factor analysis of the 20-item CLDH scale suggested a two-factor structure—career and life development pathways (CLDP) and career and life development agency (CLDA)—which accounted for 63.08% of the total variance. The confirmatory factor analysis results show a good model fit (CFI = 0.934, TLI = 0.926, RMSEA = 0.060, 90% CI [0.055, 0.065], SRMR = 0.042) and all the items significantly represented the corresponding sub-constructs. The results also demonstrate a satisfactory internal consistency for all subscales and the full scale (0.89–0.95). Sub-group consistency across subsamples categorized by gender, age, and years of residence in Hong Kong was indicated. Correlations between the CLDH scale and subscales with other career-related and social well-being outcomes (i.e., youth career development competency, career adaptability, civic engagement, social contribution, and social integration) showed good concurrent validity. Our results support that the CLDH scale is a valid and reliable tool for measuring NEY’s hope for career and life development in the Hong Kong context. Theoretical and practical implications of the findings are also discussed.