Background <p>Although many studies have estimated the prevalence of chronic kidney disease (CKD) in the general population, few have assessed its cumulative incidence over a long time using both estimated glomerular filtration rate (eGFR) and albuminuria or assessed how CKD occurrence influences mortality.</p> Methods <p>This prospective, population-based cohort study included 1144 Finnish participants aged 40–65 years at baseline, who were followed from 1996 to 2019. The study assessed the prevalence of CKD stages 1–5 at baseline, 10 years, and 22 years, and examined risk factors for incident CKD, defined as a ≥ 40% decline in eGFR, new-onset proteinuria, or a new kidney disease diagnosis. It also evaluated the association between incident CKD, eGFR decline, and proteinuria and mortality. Multivariable Cox proportional hazards models were used to assess risk factors of incident CKD, and the effect of eGFR decline or proteinuria on mortality.</p> Results <p>At baseline, the prevalence of CKD was 3.1%. During the follow-up, incident CKD was detected in 14.1% of participants. In multivariable analysis, older age, higher body mass index, diabetes and hypertension were associated with increased risk of CKD. After adjustment for age, incident CKD was associated with 2.31-fold risk of all-cause mortality, and when evaluated separately, proteinuria and a ≥ 40% decline in eGFR were associated with 2.75-fold and 2.37-fold risks, respectively.</p> Conclusion <p>Incidence of CKD is high in middle-aged Finns and is strongly associated with increased mortality.</p>