The relationship between health and subjective well-being (SWB) has been broadly examined, however it has mainly been done from a unidirectional point of view. This paper addresses the simultaneous association between health-related quality of life (HRQoL) and life satisfaction, measured by means of the preference-based SF-6D utility score and the Satisfaction With Life Scale (SWLS), respectively. The study sample consisted of 870 individuals from the Spanish general population, aged 18 to 90. We found that the unobserved factors that determine the SF-6D utility score and life satisfaction are significantly related and that, by ignoring simultaneity, the effect of life satisfaction on the SF-6D utility score is underestimated by nearly 22%, whilst the magnitude of the bias in the opposite direction effect is much lower. Once simultaneity is taken into account, the effect of the SF-6D utility score on life satisfaction is slightly higher than the reverse effect. These findings suggest that health policies should be assessed not only by their direct impact on HRQoL, but also by their induced effect on life satisfaction.