This study deals with the facies architecture of the Cenomanian Ain Tobi Formation along Nafusah Escarpment (NE), Northwest Libya. The Ain Tobi succession was deposited broadly on a shallow carbonate ramp setting. Five detailed sections were measured from the northeastern to the southwestern parts of the NE and logged using the standard logging technique. Sixty thin sections were examined and interpreted better to understand the vertical and lateral facies variations through time. Six leading facies associations (FA-I to FA-VI) were identified. Peritidal facies association (FA-I) is characterized by red/yellow colored sandstone, microbial laminated bindstone with locally desiccation cracks, skeletal wacke-packstone with mechanical lamination, and sandy skeletal float-packstone with locally erosive base and oriented bioclasts. Rudist biostorm of ramp interior (FA-II) comprises sandy rudistic float-rudstone deposited within the lagoon. Shallow lagoonal subtidal (FA-III) consists of bioturbated mudstone/wackestone, packstone, and floatsone with locally wavy ripples. Deep lagoonal subtidal (FA-IV) mainly comprises marlstone and marly claystone. Shoal (FA-V) comprises cross-bedded oolitic, peloidal, and skeletal packstone/grainstone. Rudist bank and forebank (FA-VI) is characterized by scattered communities of rudist build-up, and these rudist shells redeposited basinward in the forebank as massive rudistic skeletal wackestone/floatstone. These facies are highly dolomitized. The Ain Tobi Formation represents a major third-order transgressive–regressive succession developed on the northern African passive margin during greenhouse conditions. The Formation has been subdivided into four fourth-order cycles in the northeastern parts of the NE and only three cycles in the southwestern part. These Cenomanian depositional sequences probably coincide with global glacio-eustatic cycles that are driven by the long eccentricity variation. Both eustatic sea-level change and paleotopography were the primary controls on spatial facies distributions and thickness variations.