Purpose – Drawing on self-determination theory (SDT) and Herzberg's two-factor theory, this study examines how extrinsic motivation, which arises from the conditions surrounding work, and intrinsic motivation, which arises from the work itself, are jointly associated with employees' innovative work behavior (IWB), and whether one form is more strongly associated with IWB than the other. It responds to the tendency of earlier research to study a single motivational form, which leaves the combined and relative contributions of the two forms unclear. Design/methodology/approach – A cross-sectional census survey was conducted in 2026 among all 144 employees of a private-sector population, which gave a response rate of 100%. Using structural equation modeling (PLS-SEM) in SmartPLS 4, using 5,000 bootstrap resamples. Originality – The study estimates extrinsic and intrinsic motivation, specified through the two-factor and self-determination perspectives, simultaneously in a single parsimonious PLS-SEM model, and complements the usual path coefficients with effect sizes and a formal comparison of the two paths. Using a fully enumerated private-sector population, it offers context-specific evidence on how motivation arising from the work context and motivation arising from the work itself stand relative to each other in explaining IWB. Findings and Discussion – The measurement model showed adequate reliability and validity (outer loadings .678–.834, composite reliability .821–.881, AVE .535–.636, HTMT ≤ .469). Extrinsic motivation (β = .340, p < .001) and intrinsic motivation (β = .239, p < .001) were both positively associated with IWB and together explained 21.8% of its variance (R² = .218). The effect size of extrinsic motivation was small to medium (f² = 0.136) and that of intrinsic motivation was small (f² = 0.067), but the difference between the two path coefficients was not statistically reliable. Practical implications – Managers who want to stimulate innovation should treat the context and the content of work as complementary levers rather than substitutes: keep the workplace comfortable, allow time to rest and support collaboration among colleagues, and provide recognition, ability-matched training and learning opportunities that make the work itself satisfying. Because motivation accounts for roughly one-fifth of the variance in IWB, these levers should be combined with climate, leadership and capability-building measures.