Peste des petits ruminants virus (PPRV) is a transborder viral infection with high morbidity and mortality in small ruminant populations, threatening the global livestock economy. The risk of transient immunosuppression and the lack of divergence (DIVA) between naturally infected and vaccinated animals in current live attenuated vaccines necessitate the development of next-generation prophylactic strategies. This highlights the need for safer, alternative vaccine platforms. Here, a multi-epitope mRNA vaccine candidate potentially compatible with a DIVA strategy was designed, targeting the structural F, H, and N proteins of PPRV. By analyzing global consensus sequences, 15 cytotoxic and 6 helper T lymphocyte epitopes that proved to be antigenic, non-toxic, and non-allergenic were selected. To boost mucosal immune responses, ovine beta-defensin-3 (sBD-3) was integrated as an adjuvant, connecting the components with appropriate rigid and flexible linkers. Codons were optimized for ovine expression systems, yielding a 1.680-nucleotide mRNA construct. This optimized sequence showed high translational potential (CAI: 0.916) and strong intracellular stability (MFE: -716.700 kcal/mol). Structural predictions and subsequent validation indicated an intrinsically disordered architecture for the protein backbone. Molecular docking demonstrated that the vaccine construct interacts effectively with the ovine TLR4/CD14 complex and the CD150/SLAM receptor. Following this, 100 ns all-atom molecular dynamics simulations verified that the sBD-3 adjuvant forms a highly stable complex at the ovine TLR4 interface. Computational immune simulations suggested that a standard three-dose vaccination protocol could trigger humoral and cellular immunogenic profiles, characterized by Th1 polarization and long-lasting memory. Overall, this bioinformatic study proposes an mRNA-based alternative that bypasses the biosafety issues of conventional PPRV vaccines, offering a solid basis for future in vivo and in vitro experimental validation.