This study developed and validated the niyama-based spiritual well-being scale (NSWBS) using a mixed-method approach. Niyama is one of the eight limbs of ancient Indian Ashtanga yoga philosophy. There are five niyamas: soucha (internal and external cleanliness and hygiene), santosha (happiness and contentment), tapas (austerity and discipline), swadhyaya (self-study, observation and self-introspection) and ishvara-pranidhana (believe and surrender to the God and cosmic power). Both deductive (using existing spiritual well-being scales) and inductive (focus group discussions) approaches were used to generate items. These statements were first subjected to content validity testing and pre-testing, which resulted in seventeen statements. The psychometric properties of generated items were analyzed with the help of three independent studies that utilized various statistical tests like exploratory factor analysis (EFA), confirmatory factor analysis (CFA), Cronbach's alpha, McDonald Omega, Average variance explained, and Fornell and Larcker criterion. The first study examined the factorial structure of the proposed scale. EFA yielded five factors: Internal and external health and purity, Self-discipline and rigour, Self-introspection and observation, Contentment and gratitude, and Belief in God and higher cosmic power. They explained 62.35% of the total variance. The CFA validated the five factorial structure of the scale. The second study established the proposed scale's internal consistency reliability, convergent, divergent, and predictive validities. Lastly, the third study evaluated and concluded the test-retest reliability of the scale. Overall, the niyama-based spiritual well-being scale depicted appreciable psychometric properties.