Purpose: Accurate interpretation of cardiorespiratory fitness (CRF) requires reference values that account for sex, age, and body composition. Existing reference values often lack these distinctions or exclude older adults. This study aimed to establish sex- and age-specific reference values for absolute and relative (body mass-corrected and lean body mass-corrected) CRF parameters derived from cardiopulmonary exercise testing (CPET) in Dutch community-dwelling 55- to 75-year-old adults. Methods: Cross-sectional data from 611 participants of the AMCOHF study were analyzed. CRF was assessed via cycle ergometer CPET evaluating oxygen uptake (V̇O_2peak) and work rate (WR_peak) at peak exercise, oxygen uptake at the ventilatory anaerobic threshold (V̇O_2VAT), and oxygen uptake efficiency slope (OUES). Body mass and lean body mass were measured using dual-energy X-ray absorptiometry. Reference values stratified by sex and age were developed using generalized additive models. Prediction equations were generated using multiple linear regression. Correlations with V̇O_2peak assessed the usefulness of V̇O_2VAT and OUES as submaximal and effort-independent alternatives for CRF. Results: All CRF variables declined with age. V̇O_2peak (L/min) declined quasi-linearly (females: 1.3%/year; males: 2.5%/year). Significant sex differences were observed between all CRF variables (absolute and body mass-corrected values: p < 0.001; lean body mass-corrected values: p < 0.05). Significant correlations were found between V̇O_2peak and WR_peak (ρ = 0.90), V̇O_2VAT (ρ = 0.78), and OUES (ρ = 0.87). Conclusion: This study provides reference values for V̇O_2peak, WR_peak, V̇O_2VAT, and OUES in Dutch older adults aged 55–75 years during cycle ergometer CPET, offering a unique dataset for assessing CRF and monitoring intervention effects.