Background The intrauterine device (IUD), being a reversible and effective contraception method, is the most widely used worldwide. This study aims to demonstrate the efficacy of IUD insertion during elective lower segment cesarean section (LSCS) versus its insertion six weeks postpartum. Methods A cohort study was conducted on 200 women planned for elective cesarean delivery and desired IUD as a contraceptive method. They were allocated into two groups; group I, in which IUD was inserted during LSCS, and group II, in which IUD was inserted six weeks or more after LSCS. Both groups were compared regarding failed insertion, post-insertion pain, and uterine perforation. They were followed for one year for the incidence of menorrhagia, vaginal infection, IUD displacement/expulsion, missed threads, or unintended pregnancy. Results Women in the second group showed a significantly higher incidence of failed insertion and uterine perforation than women in the first group. On the contrary, women in the first group showed a significantly higher incidence of missed threads than women in the second group. Regarding other consequences, there were no significant differences between both groups concerning menorrhagia, vaginal infection, IUD displacement/expulsion, or unintended pregnancy. Conclusion IUD insertion during elective LSCS showed a significantly lower incidence of failed insertion and uterine perforation than its insertion six weeks postoperative.