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<i>Streptococcus bovis</i> (<i>S. bovis</i>) is one of the critical initiators of acute acidosis in ruminants. Therefore, we aimed to develop and characterize the endolysin LyJH307, which can lyse ruminal <i>S. bovis</i>. We tested the bactericidal activity of recombinant LyJH307 against <i>S. bovis</i> JB1 under a range of pH, temperature, NaCl, and metal ion concentrations. <i>In silico</i> analyses showed that LyJH307 has a modular design with a distinct, enzymatically active domain of the NLPC/P60 superfamily at the N-terminal and a cell wall binding domain of the Zoocin A target recognition domain (Zoocin A_TRD) superfamily at the C-terminal. The lytic activity of LyJH307 against <i>S. bovis</i> JB1 was the highest at pH 5.5, and relatively higher under acidic, than under alkaline conditions. LyJH307 activity was also the highest at 39 °C, but was maintained between 25°C and 55°C. LyJH307 bactericidal action was retained under 0-500 mM NaCl. While the activity of LyJH307 significantly decreased on treatment with ethylenediaminetetraacetic acid (EDTA), it was only restored with supplementation of 10 mM Ca²⁺. Analyses of antimicrobial spectra showed that LyJH307 lysed Lancefield groups D (<i>S. bovis</i> group and <i>Enterococcus faecalis</i>) and H (<i>S. sanguinis</i>) bacteria. Thus, LyJH307 might help to prevent acute ruminal acidosis.