This study investigates the association among metabolic risk factors, inflammatory and oxidative stress markers, and brachial–ankle pulse wave velocity (ba-PWV). We conducted a 3-year longitudinal, observational study of 288 middle-aged adults not meeting the criteria for metabolic syndrome (MetS) at the initial screening. We measured metabolic risk factors, inflammatory and oxidative stress markers, and ba-PWV. Within the 3-year study period, 15.6% (45 out of 288) of participants developed MetS. At the 3-year follow-up, patients were categorized as those with MetS (n = 45) and those without MetS (n = 243). Patients with MetS had significantly unfavorable initial measurements of baseline body mass index (BMI), waist circumference (WC), blood pressure (BP), triglyceride (TG), high-density lipoprotein (HDL)-cholesterol, glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR) index, and ba-PWV. After 3 years, participants without MetS showed significant increases in WC, diastolic BP (DBP), total- and low-density lipoprotein (LDL)-cholesterol, malondialdehyde (MDA), oxidized-LDL (ox-LDL), and ba-PWV and a significant decrease in HDL-cholesterol and free fatty acids (FFA). Subjects who developed MetS showed significant increases in BMI, WC, BP, TG, glucose, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), MDA, ox-LDL, and ba-PWV and a significant decrease in HDL-cholesterol. Changes in BMI, WC, BP, TG, HDL-cholesterol, glucose, HOMA-IR index, FFA, C-reactive protein (P = .022), IL-6 (P = .004), leukocyte count (P < .001), MDA (P = .002), ox-LDL (P = .015), and ba-PWV (P = .001) differed significantly between the two groups after adjustment for baseline values. Changes in ba-PWV were positively correlated with the changes in systolic and DBP, total-cholesterol, glucose, leukocyte count, and MDA. The age-related increase in arterial stiffness is greater in the presence of MetS with higher levels of inflammatory and oxidative stress markers.