Avocado is the most important fruit with high nutritional value in the tropics and subtropics. It is a widely grown cash crop in south, southwest, and east part of Ethiopia. The quality of avocado fruits can be evaluate based on worldwide accepted indicators of fruit quality i.e., moisture content, pH, total soluble solid, acidity, ash content, fat content, and protein content. In Ethiopia, the fruit quality of different varieties has been studied based on effect of agroecology location. However; the fruit nutritional values and phytochemical contents of different varieties at different stages of maturity has not been yet reported. Therefore, the main purpose of this study was to investigate the effect of maturity stages in relation to varieties of avocado fruits on their nutritional and phytochemical quality Four varieties of avocado fruits (Hass, Fruet, Ettinger and Nabal) at three different maturity stages (early or unripen, mid or ripen, and late or over ripen stages) were collected from Wachemo University, Agricultural Research and Technology Transfer Center, Lambuda Research Farm, Central Ethiopia Region, Ethiopia. Two different trends were observed in this study. Highest physiochemical properties (TSS (10.80), Ash content (2.29) and TSS: TA ratio (67.5), highest phytochemical content (vitamin C (2.95), TPC (94.23) and TFC (54.84) were observed in mid stages. At this stage, Ettinger followed by Hass showed highest contents among all varieties and also observed lowest pH (6.17) and moisture content (78.44) when compared with corresponding stage with other varieties. However; highest fiber (20.1%), TA (0.26%), carotenoid (25.81mg/100g) and protein (1.59%) contents were observed in early stage and highest fat content was observed in late stage (81.19%). At these stages, Ettinger followed by Hass also showed highest contents among all varieties except carotenoid which have highest in fruete. The obtained results indicated that stages of maturity had significant effect on the quality indicators and phytochemical contents among all varieties of avocados fruits. The study showed Significant difference (P>0.05) between investigated parameters was noted between early, mid and late stage of fruits among all varieties of fruits except pH measurements. The results revealed that investigated parameters (physicochemical, proximate composition and phytochemical analysis) are vary within variety and maturity stages. Therefore, this research would be identified optimal avocado maturity stages and variety for superior nutritional quality, providing valuable information for consumers, the industry, and farmers. It is recommended for avocado cultivation and consumption to maximize nutritional benefits.