Nearly 90% of people’s lives are lived indoors, and their health is affected by the concentrations of CO₂ in these spaces. Carbon dioxide concentrations can rapidly change based on human activity in indoor living spaces. Indoor plants and the concentration of CO₂ in the local environment are factors that influence most people. Plants, depending on the ambient light and temperature conditions, and which are necessary to perform photosynthesis or respiration, directly affect the concentration of CO₂ in the local environment. Furthermore, indoor plants influence the level of CO₂ in the local environment but have not been researched enough in recent years concerning their specific effects. This study attempts to determine the effects of indoor plants on the concentration of CO₂ in an indoor environment under certain light conditions. Five indoor plants were placed in a glass-walled compartment in order to measure the amount of CO₂. The glass compartment used in the study was positioned in a way to prevent direct sunlight yet provide an illuminated environment. The plants were placed into this airtight compartment with a glass wall, which had a volume of approximately 0.5 m³ (0.7 m x 0.7 m x 1 m). The measurements of CO₂ within the compartment were carried out via Extech Desktop Indoor Air Quality CO₂ Datalogger, and the CO₂ measuring device placed in the compartment was set to measure CO₂ once every five minutes. The study found that all plants reduced the concentration of CO₂ to a certain extent during the day.