Reproductive efficiency is a key determinant of the profitability and sustainability of sheep farming systems, particularly in arid and semi-arid regions. In Algeria, declining flock productivity—exacerbated by recurrent droughts, forage scarcity, and thermal stress—has raised concerns about the resilience of extensive and semi-intensive sheep production. This study aimed to compare the efficacy of hormonal synchronization, vitamin AD₃E supplementation, and their combination on the reproductive performance of Rembi ewes during seasonal anestrus. Conducted in spring 2024 on a semi-intensive farm in Aïn Bouchakif (Tiaret, Algeria), the trial involved 60 healthy pluriparous ewes randomly assigned to three groups (n = 20). Group 1 received hormonal treatment (intravaginal progestogen-impregnated sponges followed by PMSG), Group 2 received the same hormonal protocol combined with monthly AD₃E injections, and Group 3 received vitamins only. Fertility, fecundity, prolificacy, birth weight, and neonatal mortality were evaluated. Principal Component Analysis (PCA) was applied to explore multivariate patterns. The combined treatment (Group 2) yielded the best reproductive outcomes: 100% fertility, 160% fecundity, and 0% neonatal mortality. Group 1 recorded the lowest fertility (80%) and highest neonatal mortality (16.66%), while Group 3 achieved the highest average birth weight (4.25 kg) but lower prolificacy. PCA revealed three distinct reproductive profiles, clearly differentiating the protocols' effectiveness. These results underscore the synergistic benefit and practical advantage of combining hormonal synchronization with vitamin supplementation to improve fertility and prolificacy while reducing neonatal losses. This integrative strategy offers a viable and sustainable approach to enhancing reproductive performance in Rembi ewes under the challenging conditions of Western Algeria's steppe regions.