Mammals have a duplex retina, with rods for dim-light vision and cones for daylight and color vision. In most mammals rods predominate. Cone dominant retinas are exceptional and have been reported, e.g., for species in the rodent suborder Sciuromorpha. The Eurasian red squirrel (Sciurus vulgaris) is a representative of Sciuromorpha with excellent daylight vision. This study aimed to provide detailed information on the photoreceptors of this species for the first time. Eyes from S. vulgaris of different age and both genders were examined. Rods and spectral cone types were immunolabeled with cell type-specific markers in retinal frozen sections and wholemounts and evaluated by fluorescence microscopy to determine the presence, number, and density distribution of photoreceptor types. We found that rods, shortwave-sensitive (S) and middle-to-longwave-sensitive (M) cones were present and distributed across the entire retina. Rod densities increased from dorsal (47,000/mm²) to ventral retina (78,000/mm²). Cone densities increased from peripheral (21,000/mm²) to central retina (46,000/mm²), with peak values in a horizontal streak ventral of the papilla. Rod to cone ratios were 2 to 1. M cones comprised the major cone population (20,000 to 43,400/mm²). S cone densities ranged from 1,000 to 2,600/mm². Ratios of S to M cones were 1:17 to 1:20. We found no evidence for coexpression of opsins in single photoreceptors. Our results demonstrate clear species differences within Sciuromorpha. The retina of S. vulgaris is cone-rich but rod-dominated, which may be of adaptive advantage in a diurnal animal with arboreal lifestyle.