An Android-based mobile application called the Indoor Air Quality Monitoring and Recommendation System (AIRZEN) can help the FEU Tech’s Facilities Office (FO) and general Indoor spaces in assessing the Air Quality inside indoor spaces. This system is a tool used to monitor and check the Air Quality inside Indoor spaces as well as give recommendations to help mitigate the effects of bad Indoor Air Quality. The KNN algorithm was utilized for the prediction of the AQI value and classification of Recommendations. To determine whether the system works as intended, testing was administered together with a survey participated by 50 respondents consisting of professionals from the IT/CS/IAQ Industry, IT/CS/CPE students, IT/CS Faculty, and Office workers. This capstone project’s output received an Above Average rating of (4.56) in terms of Functionality, Reliability, and Efficiency. Future researchers can make system improvements by adding a Backup and Restore feature for times of data outage as well as an Ios integration for a bigger range of users. An additional Recommendation is also to add feedback from existing users inside the application as well as a notification system that notifies users while they are out of their homes. The proponents also recommend the implementation of multiple monitoring device support for bigger scalability.