Abstract Background Religiosity is a system of worship and doctrine that is shared by a group, and spirituality is the individual search for the meaning of life. The relationship between spirituality/religiosity (S/R) and health has a long history, and a positive correlation between spirituality and chronic diseases has been described in scientific literature, showing a decrease in morbidity and mortality in general. Objective To evaluate the association between S/R and the quality of life of patients with diabetes and/or systemic arterial hypertension. Method An observational, analytical, cross-sectional, quantitative study was conducted with a sample consisting of 40 patients treated at the hypertension and diabetes outpatient clinic of a medical center in Recife. The collection used three assessment instruments (SSRS, Duke-DUREL scale, and WHOQOL-BREF). Data from the questionnaires were analyzed using descriptive (frequency and percentage) and inferential statistics (chi-square test and F test) using the R software, version 3.4.3. The level of significance in all analyses was 5%. The study was approved by CEP/IMIP, according to report no. 2.890.126. Result All four domains of the quality-of-life scale (WHOQOL-BREF) showed a positive relationship when correlated with the religiosity scale (DUREL), with statistical significance in the relationship between organizational religiosity and the environmental domain. When correlated with the spirituality scale (SSRS), WHOQOL-BREF also showed a positive relationship, except in the physical domain. Conclusion A positive relationship between quality of life and S/R was shown, thus confirming its importance for patients with diabetes and SAH.