Fish-specific piscidins are important antimicrobial peptides in teleost innate immunity, but their host-directed antiviral mechanisms remain unclear. In this study, we investigated the immune-priming effects of largemouth bass MsPiscidin1 and MsPiscidin3 in MSDF cells. Because these peptides protect host cells from MSRV infection without strong evidence of direct virucidal activity, we performed phosphoproteomic analysis of MSDF cells treated with MsPiscidin1, MsPiscidin3, or vehicle control for 24 h. The aim was to define phosphorylation-associated cellular changes induced by peptide priming before viral challenge. The resulting dataset identified phosphoprotein signatures related to membrane remodeling, vesicle trafficking, autophagy, PI3K–mTOR signaling, ubiquitin-dependent regulation, and innate immune-related pathways. These data provide a useful reference for exploring how piscidins establish an antiviral-ready cellular state and for identifying candidate regulators of fish AMP-mediated immune priming.