Abstract The application of microalgae in wastewater treatment has attracted the attention of researchers since a few decades ago. Palm oil industry is one of the lucrative main exporting industry in Malaysia which has drawn the attention of researchers in mitigating the polluting impacts caused by the palm oil mill effluent (POME) released from the oil palm processing. In this study, the growth of the green algae Chlorella vulgaris and Chlamydomonas reinhardtii in the pre-treated POME was studied for 7 continuous days. The number of microalgae cells, chlorophylls and carotenoids contents were monitored throughout the cultivation period. The potential of both strains of microalgae as the water polisher for post-treatment of POME was investigated as well. The findings revealed that both microalgae showed lag phase at the beginning of cultivation and grew exponentially later. When monitoring the chlorophyll content, chlorophyll a and chlorophyll b played a role in photosynthesis when the microalgae detected environmental changes. The carotenoids in the microalgae acted as the accessory pigments which assisted in light harvesting under poor light condition and as the antioxidant protecting the cells when there was excess light. C. vulgaris was able to remove 98.1 % of phosphate and 53.1 % of ammoniacal nitrogen while C. reinhardtii removed 90.1 % and 37.3 %, respectively. This study indicated that two microalgae species have a high potential to be integrated in the post-treatment for POME.