Background <p>This research examines the impact of bariatric procedures on male sex hormones and semen parameters in infertile men with obesity. Obesity adversely affects male fertility by causing hormonal imbalances and worsening semen quality. Metabolic and bariatric surgery (MBS) offers sustained weight loss and potential reversal of these abnormalities.</p> Methods <p>This prospective case series included 43 infertile men with severe obesity who underwent sleeve gastrectomy, One-anastomosis gastric bypass (OAGB), or Roux-en-Y gastric bypass. All participants had a BMI ≥ 35&#xa0;kg/m² and a history of infertility for over one year. Semen analysis and hormonal profiling (FSH, LH, total testosterone, estradiol [E2], and prolactin) were conducted preoperatively and at 3, 6, and 12 months postoperatively.</p> Results <p>Significant weight loss was observed at all follow-up points (<i>p</i> ≤ 0.003). Improvements were noted in semen motility, progressive motility, vitality, and abnormal forms (all <i>p</i> ≤ 0.003). Serum testosterone levels increased, while estradiol levels decreased significantly (<i>p</i> ≤ 0.003). Changes in FSH, LH, and prolactin were statistically insignificant.</p> Conclusions <p>Metabolic and bariatric surgery (MBS) is associated with marked improvements in semen quality and serum testosterone levels, supporting its role as an effective therapeutic strategy for obesity-related male infertility. No pregnancies were recorded during the 12-month follow-up.</p> Trial registration <p>Not applicable.</p>