Aims: Marine bacteria have been reported to produce potential natural pigment with pharmaceutical properties and their growth can be manipulated in the laboratory to increase pigment production and their antimicrobial activity. Hence, this study aimed to enhance the prodigiosin production in Serratia marcescens IBRL USM84 by improving physical conditions. Methodology and results: The quantification of the pigment produced by S. marcescens IBRL USM84, bacterial cell growth, and its antibacterial activity in the broth medium were determined using a spectrophotometry method. Meanwhile, the antibacterial effect of red pigment on MRSA cells was observed under a scanning electron microscope (SEM). This marine isolate produced the highest yield of prodigiosin (6.95 µg/mL) when cultivated in marine broth with the addition of 0.2% of agar, 25 °C incubation temperature, initial medium pH of 7, 150 rpm of agitation speed for 48 h of cultivation time under light illumination. There was an increment of 151.81% in prodigiosin production after enhancement compared to before the enhancement of cultural conditions. SEM observations revealed that severe damage to the cell's morphologies was exposed to red pigment as indicated by the formation of small dents, which led to completely collapse and eventually, cell death. Conclusion, significance and impact of study:A positive correlation between pigment production and antibacterial activity was observed in the present study. The results supported the fact that marine bacteria are a reservoir of various pigments with antimicrobial properties. Also, the pigment production by S. marcescens and its antibacterial activity were significantly influenced by physical parameters.