The ocean, a mother of all life, supports a vast microbial diversity, with marine bacteria being key producers of valuable molecules like carotenoids with various valuable biological properties and applications. The present research aimed to study the effect of one-factor-at-a-time (OFAT) such as pH, temperature, media (marine broth and nutrient broth), carbon sources (maltose, lactose, glucose, and sucrose), nitrogen sources (peptone, yeast extract, ammonium sulfate, and urea), and salts (MgCl2, MgSO4, CaCl2, and NaCl) on growth and pigment production. Response Surface Methodology (RSM) was used to further improve lactose, yeast extract, and magnesium sulfate significant components selected from the OFAT technique. The optimized medium consisted of 5 g/l lactose, yeast extract, and MgSO4. The maximal biomass in RSM optimized medium was 12.58 g/l and the carotenoid yield was 147.58 ± 2.48 mg/l, in the validated model. When compared to the unoptimized medium, we discovered that the optimized fermentation medium allowed a 3.45-fold increase in carotenoids and a 1.97-fold increase in biomass production of B. infantis. This is the first research on carotenoid production by marine Bacillus infantis, offering a novel source of natural carotenoids. The result suggests that the Response Surface Methodology improved yield and helped control the fermentation process.