<p>The Blue Nile Basin is one of the five main sedimentary Basins in Ethiopia which has a contemporaneous origin with the petroliferous Ogaden Basin. Since the Blue Nile Basin has good petroleum prospect, reconstructing its paleodepositional environment is key to unravel the nature of the reservoir rocks in the Basin. Fieldwork and microscopic examination were carried out in the carbonates of the Antalo limestone Formation exposed throughout the Blue Nile Basin, to determine paleoenvironments and understand depositional history. Based on microfacies and sedimentological analysis, sixteen (16) microfacies types related to shallow marine homoclinal carbonate ramp are identified. The facies associations were assigned to specific ramp environments through integrated analysis of sedimentological, paleontological content, and textural characteristics observed in thin sections. The facies analysis revealed the recognition of three inner ramp facies associations of tidal flat, inner lagoonal and outer lagoonal which characterize the lower part of the formation. The middle section transitions to a mid-ramp setting with high-energy shoal and shallow marine facies. The upper part indicates a shift to deep open marine environments (outer ramp and deep Basin). However, the very top layer indicates a return to inner to middle ramp environments, with the shoal and lagoon facies depicting a return to shallower environments. The distribution of facies associations indicates that an overall deepening upward sequence, characteristics of carbonate ramp. The vertical variations in the facies suggests sea-level fluctuations within the basin. Regionally, the depositional model aligns with other Ethiopian sedimentary basins, such as Mekele Basin, which show comparable carbonate ramp model. It also similar with ramp models of Tethyan carbonate systems offering insights into hydrocarbon exploration. It also enhances global comparisons with other marine carbonate sequences.</p>