Cardiovascular disease is one of the leading causes of death worldwide. Evidence suggests that alterations in the gut microbiome could play a role in cardiovascular diseases, including heart failure. The purpose of this study was to evaluate the effect of synbiotics on serum paraoxonase 1(PON1), soluble CD163/soluble TNF-like weak inducer of apoptosis (sCD163/sTWEAK), and lipid profile, which are involved in heart failure in patients with chronic heart failure. In this triple-blind randomized clinical trial, 90 eligible patients were included in the study. They were randomly assigned to receive one capsule (500 mg) of synbiotics or a placebo daily for ten weeks. Serum PON1, sCD163/sTWEAK, and lipid profiles were measured at the beginning and end of the study. The data were analyzed by SPSS 24, and the p-value < 0.05 was considered statistically significant. Among 90 patients who met the inclusion criteria, 80 completed the study. The primary outcomes showed a small effect on sTWEAK, with an adjusted standard mean difference (SMD) of 0.2. However, no significant changes were observed in sCD163/sTWEAK (SMD: 0.16). Secondary outcomes indicated no changes in PON1, total cholesterol (TC), or LDL-C levels. However, there was an increase in HDL-C levels (adjusted SMD: 0.46, 95% CI: 0.02-0.91) and a decrease in TG and TC/HDL levels (adjusted SMD: - 0.5 and - 0.3, respectively) in the synbiotic group. A favorable effect of synbiotics on sTWEAK, HDL, TG, and TC/HDL of patients with heart failure was observed, but no statistically significant effect was found on sCD163/sTWEAK, PON1, LDL, and TC factors.