Soluble Klotho (S-Klotho) is an aging suppressor with a close link with inflammation. However, it is still unknown whether the dietary inflammatory potential is associated with S-Klotho plasma level. We aimed to investigate the association of the Dietary Inflammatory Index (DII) with S-Klotho plasma levels in middle-aged sedentary adults. 73 middle-aged sedentary adults (40–65 years old) participated in the present study. DII was determined from 28 dietary items obtained by 24 h recalls and food frequency questionnaires. The S-Klotho plasma levels were measured using a solid-phase sandwich enzyme-linked immunosorbent assay. a weak positive association was observed between DII and S-Klotho plasma levels (β = 52.223, R² = 0.057, p = 0.043), which disappeared after controlling for body mass index (p = 0.057). A pro-inflammatory dietary pattern measured with the DII was slightly and positively associated with S-Klotho plasma levels in middle-aged sedentary adults.