The Department of Botany and Microbiology, under the College of Science,  is an educational and research organization dedicated to the development of human resources and the diffusion of knowledge in the different fields of Botany and Microbiology. The Department is striving hard to evolve into one of the best Botany departments among the various universities in the Kingdom of Saudi Arabia and the Arab world. The Department provides excellent opportunities for higher education in accordance with the high academic standards in all areas of advanced and specialized areas of plant sciences and microbiology. The Department has acquired capabilities to provide trained manpower at all levels towards the overall development through their education in the Ministry of Education and Higher Education Saudi Arabia, and other universities and the Ministry of Health and the Ministry of Agriculture, and the Ministry of Water and Power and the Ministry of Commerce, Industry and the authority of specifications and standards, the National Authority for the protection of wildlife, development and PE Meteorological and Environmental Protection and private institutions. The Department contributes to the development of knowledge through intensive scientific research at basic and advanced levels in the field of plant sciences and Microbiology besides augmentation of trained human resources, providing consulting services to production and developmental authorities with practical solutions and specialized counseling to help them perform their duties and their role in overall development. Further, the Department has a keen interest in enhancing the awareness of the intellectual and cultural community and the protection of the environment

This Department was established in the College of Science in 1958 G (1378 H) to prepare specialized qualified scientific cadres, still contributing to achieving the progress of our sincere nation (Kingdom of Saudi Arabia) in so numerous fields such as general and higher education, health, agriculture, and society employ. It is the oldest Department interested in studying the plant sciences at KSA. At the beginning of 1403/1404, the girls' branch of the Department was established in the KSU study center in Malaz- Al-Riyadh. In 1407H (1978G) the field of Microbiology was established as a branch beside Botany. Since that time, the Department was renamed as Department of Botany and Microbiology, and has been offering the B.Sc. degree in Botany, Microbiology.

At 1401H (1981G), the postgraduate study started as M.Sc. in Botany, and at 1413H (1993G), the M.Sc. plan was modified so that the Department could offer two M.Sc. degrees, in Botany and Microbiology. The Ph.D. plan in both Botany and Microbiology started at 1417H (1997G).

The Department occupies the western northern part of Building 5 of the Faculty of Sciences. It includes study rooms, 20 student laboratories, and 28 scientific research laboratories equipped with many updated instruments. The Department also contains a Herbarium that is considered an important reference for the plants of the Arabian Peninsula. In this Herbarium, the plants are reserved in a special way that they appear in their natural form. Joined with the Department, is a botanical garden containing many wild plants belonging to different environmental models. Both the Herbarium and the Botanical Garden are utilized in practical undergraduate and postgraduate studies. The Department includes a branch in the KSU Studies Center for Girls. The affiliation of Department currently has more than 40 members of the faculty in different certain specializations in the fields of Botanical and Microbiological sciences, and a number of lecturers, assistant researchers, demonstrators, and technicians. The Department sends a number of its postgraduate students for scientific qualifications in different disciplines according to the plan of the Department in the completion of faculty members of the national component. The Department also has a service unit (Central Research Laboratory) containing the most updated technical equipments in addition to an integrated micro preparations unit to assist in the scientific research projects and experiments for members of the faculty and postgraduate students.