OBJECTIVES: To assess age, period, and birth cohort effects and patterns of obesity-attributable mortality in Czech Republic, Finland, France, Germany, Hungary, Italy, Poland, and the UK (UK). METHODS: We obtained obesity prevalence and all-cause mortality data by age (20-79), sex and country for 1990-2012. We applied Clayton and Schifflers' age-period-cohort approach to obesity-attributable mortality rates (OAMRs). RESULTS: Between 1990 and 2012, obesity prevalence increased and age-standardised OAMRs declined, although not uniformly. The nonlinear birth cohort effects contributed significantly (p < 0.01) to obesity-attributable mortality trends in all populations, except in Czech Republic, Finland, and among German women, and Polish men. Their contribution was greater than 25% in UK and among French women, and larger than that of the nonlinear period effects. In the UK, mortality rate ratios (MRRs) increased among the cohorts born after 1950. In other populations with significant birth cohort effects, MRRs increased among the 1935-1960 cohorts and decreased thereafter. CONCLUSIONS: Given its potential effects on obesity-attributable mortality, the cohort dimension should not be ignored and calls for interventions early in life next to actions targeting broader societal changes.