A field survey was conducted to assess plant species diversity of homegarden agroforestry system and its benefits to household in Umuahia North Local Government Area, Abia State, Nigeria. A multi stage sampling technique was used to select eighty households for data collection. Descriptive statistics such as mean, percentage, frequency distribution and table were used to analyze the data. A total of 72 plant species (40 woody and 32 herbaceous), belonging to 38 families were recorded. Fabaceae and Rutaceae were the most diverse among the woody species while in the herbaceous species, Solanaceae and Poaceae were the dominant families. Food production (89%) was the main benefit derived from the homegardens. Other benefits were shade (69%), medicinal and financial (68%), erosion control (24%) and beautification (43%). The result further revealed that homegarden practices pose some challenges. It was documented that 85% of the homegarden farmers have never been visited by extension agents. Agroforestry homegardens are hotspots for local plant species conservation. Some species recorded in the studied homegardens are in IUCN Red list as either vulnerable or near threatened. Adequate government initiative is vital to promote the development of the homegarden agroforestry system.