William Joseph McInnes Botanic Garden and Campus Arboretum, Botanical garden at Mills College in Oakland, United States.

The William Joseph McInnes Botanic Garden and Campus Arboretum spreads across Mills College grounds and displays California native plants, succulents, ferns, and healing plants in separate collections. The space includes greenhouses and shade structures that serve both teaching and research needs.

The William Joseph McInnes Memorial Garden, part of the Mills College Botanic Garden, was dedicated in autumn 1947 to William Joseph McInnes, a horticulturist and the husband of Blanche Rice McInnes, an alumna of the class of 1900. Blanche funded the greenhouse, the lath house and upkeep of the grounds. The garden now serves mainly as a teaching resource for the Biology Department and was still being expanded in 2010.

The garden is woven into student life and serves as a living classroom where people learn by working with plants directly. Visitors can observe how different collections support hands-on botanical education across the campus.

The garden is at Mills College, 5000 MacArthur Blvd in Oakland, Alameda County, California. Entry is free. The grounds are primarily an educational resource for the Biology Department and were still being developed and enlarged as of 2010, so some beds may be in progress.

The garden holds specialized collections of healing plants that show which local species were traditionally used for medicine. This focus sets it apart from many botanical gardens and connects plant study with practical knowledge.