Evidence indicates an association between wellbeing (e.g., purpose in life) and cognition over time. However, wellbeing is a multifaceted construct, and most research has focused on purpose in life and positive affect, with less research on other aspects of wellbeing. The aim of this study was to test associations between life satisfaction (LS) and hope with cognitive function and decline. Data were used from Whitehall II, a longitudinal cohort study of people employed by the British Civil Service. Measures of LS and hope were available at Wave 7, and cognitive function (phonemic/semantic verbal fluency, memory and inductive reasoning) at Waves 7, 9, 11, and 12. Linear mixed models were fitted to test associations between LS and hope with cognitive function and decline over 13 years. LS was positively associated with baseline cognitive function (overall cognition, verbal fluency, memory, and inductive reasoning) cross-sectionally but not with decline over time. Hope was positively associated with baseline overall cognition, phonemic fluency and inductive reasoning (but not semantic fluency or memory). Hope was associated with slower decline in inductive reasoning over 13 years. Findings contribute to better understanding of the temporal relationship between wellbeing and cognitive function from middle to older age. People with higher hope show lower baseline cognition and slower decline in inductive reasoning. People with lower LS show lower initial cognitive function and this difference is maintained over time. Although decline is not steeper for those with lower LS, they may reach the threshold for dementia earlier than those with higher LS.