Abstract Interleukin 6 (IL-6) is a circulating cytokine that is implicated in a range of inflammatory diseases. However, the broad effects of IL-6 receptor (IL-6R) signalling on other circulating cytokines is not known. Using summary-level data from genome-wide association studies, we leveraged genetic variants that proxy IL-6R signalling in two-sample Mendelian randomization analyses to investigate effects on levels of 40 circulating cytokines. Increased genetically proxied IL-6R signalling was associated with reduced levels of 10 circulating interleukins, chemokines, and growth factors. The findings from this study support feedback effects of IL-6R signalling on reducing levels of a range of circulating cytokines and identify compensatory mechanisms that may be modulating its inflammatory effects. These results provide novel insight into the mechanisms by which IL-6R signalling may be contributing to inflammatory and autoimmune diseases.