This study investigated the correlation of body mass index (BMI) and proinflammatory cytokine levels with hematopoietic stem cell (HSC) mobilization triggered by granulocyte colony-stimulating factor (G-CSF). Stem cell donors (n = 309) were recruited between August 2015 and January 2018 and grouped into four groups according to their BMI: underweight (BMI < 18.5 kg/m2, n = 10), normal (18.5 kg/m2 ≦ BMI < 25 kg/m2, n = 156), overweight (25 kg/m2 ≦ BMI < 30 kg/m2, n = 102), and obese (BMI ≧ 30 kg/m2, n = 41). The participants were then administered with five doses of G-CSF and categorized as good mobilizers (CD34 ≧ 180/μL, n = 15, 4.85%) and poor mobilizers (CD34 ≦ 25/μL, n = 14, 4.53%) according to the number of CD34+ cells in their peripheral blood after G-CSF administration. The correlation between BMI and HSC mobilization was then analyzed, and the levels of proinflammatory cytokines in the plasma from good and poor mobilizers were examined by ProcartaPlex Immunoassay. Results showed that BMI was highly correlated with G-CSF-triggered HSC mobilization (R2 = 0.056, p < 0.0001). Compared with poor mobilizers, good mobilizers exhibited higher BMI (p < 0.001) and proinflammatory cytokine [interferon gamma (IFN-γ) (p < 0.05), interleukin-22 (IL-22) (p < 0.05), and tumor necrosis factor alpha (TNF-α) levels (p < 0.05)]. This study indicated that BMI and proinflammatory cytokine levels are positively correlated with G-CSF-triggered HSC mobilization.