Introduction: Recent studies have shown that sitting time is associated with increased risk of all-cause mortality, independent of moderate to vigorous physical activity. Less is known about the population-attributable fraction for all-cause mortality associated with sitting time, and the gains in life expectancy related to the elimination of this risk factor. Methods: In November 2015, data were gathered from one published meta-analysis, 54 adult surveys on sitting time distribution (from 2002 to 2011), in conjunction with national statistics on population size, life table, and overall deaths. Population-attributable fraction for all-cause mortality associated with sitting time >3 hours/day was estimated for each country, WHO regions, and worldwide. Gains in life expectancy related to the elimination of sitting time >3 hours/day was estimated using life table analysis. Results: Sitting time was responsible for 3.8% of all-cause mortality (about 433,000 deaths/year) among those 54 countries. All-cause mortality due to sitting time was higher in the countries from the Western Pacific region, followed by European, Eastern Mediterranean, American, and Southeast Asian countries. Eliminating sitting time would increase life expectancy by 0.20 years in those countries. Conclusions: Assuming that the effect of sitting time on all-cause mortality risk is independent of physical activity, reducing sitting time plays an important role in active lifestyle promotion, which is an important aspect of premature mortality prevention worldwide.