Mahkota Dewa (Phaleria macrocarpa) also known as God's Crown has been historically used as an indispensable alternative herbal medicine. Microencapsulation is a process whereby tiny particles or droplets are engulfed or enclosed in a coating matrix to produce small capsules. Generally, without microencapsulation, powders are fragile materials that could easily interfere with other components that are difficult to dissolve in water, lose their beneficial properties and decrease shelf life. It is hoped that the microencapsulation would increase the consistency of the powder during storage and maintain its beneficial properties. The goal of this research is to investigate the physicochemical and antimicrobial activity of Mahkota Dewa leaves encapsulated in different concentrations of gum Arabic (GA) and to determine the form of antioxidant and their role and properties. Mahkota Dewa leaves powders were microencapsulated in 0%, 2%, 4%, 6%, 8% and 10% gum Arabic using an ultrasonic spray dryer at 90οC. The microencapsulated Mahkota Dewa leaves (MMDL) samples were subjected to physicochemical and antimicrobial activity. The results showed that the 6% GA MMDL exhibited the highest yield (3.91%) while 0% GA was the lowest yield (1.64%). The highest total phenolic and flavonoid content was exhibited by 2% GA. The highest DPPH inhibition was depicted in 0% GA which indicates the highest antioxidant activity (54.9±0.01%) and is significantly (p<0.05) different from other samples. The highest inhibition was exhibited in 0% GA in the TBA method and FTC analysis. The encapsulated powders were identified to have weak antimicrobial activity against Bacillus cereus, Escherichia coli, Staphylococcus aureus, Salmonella and Listeria monocytogenes. The powders produced have an irregularly spherical structure and smooth surface with some dented spots on the surface. The different concentration of gum Arabic resulted in different antioxidant activity, flavonoid content and antimicrobial activity of MMDL.