Background Cardiopulmonary exercise testing (CPET) is the gold standard for assessing physiological capacity before surgery and can predict postoperative outcomes. Socioeconomic status (SES) can impact surgical outcomes with patients from more deprived backgrounds having greater morbidity and mortality. This is the first study to analyse the relationship between SES and CPET measures in patients being considered for elective surgery. Methods Data from patients who underwent CPET between 2011 and 2024 was analysed. Patients were categorised into deprivation quintiles based on their postcode. Measures including baseline characteristics, V̇O₂ at anaerobic threshold (AT), peak V̇O₂, and VE/V̇CO₂ were compared across quintiles. Multivariable linear and logistic regression models were used to assess the effects of age, sex, BMI, Revised Cardiac Risk Index (RCRI), and deprivation quintile on CPET measures. Results A total of 3344 patients were included in the study (2476 male), who were being assessed prior to procedures in vascular (2006), colorectal (650), upper GI (267), urology (205), and other (216) surgical specialties. Lower socioeconomic status was associated with younger age (p<0.001), higher BMI (p=0.022), smoking prevalence (p<0.001), and RCRI ≥3 (p=0.013). CPET measures were less favourable in the most deprived quintile (Q1) compared to the least (Q5): mean AT was 11.0 vs. 11.5 ml·kg-1·min-1 and peak V̇O2 was 14.8 vs. 16.3 ml·kg-1·min-1 (p<0.05). Conclusion Patients from deprived areas exhibit risk factors for poor health and less favourable CPET measurements, highlighting the potential need for tailored optimisation strategies to help mitigate health disparities.