An optical fiber fan-out assembly includes multiple optical fibers arranged in a one-dimensional array in a transition segment in which spacing between fibers is varied from a first pitch (e.g., a buffered fiber diameter of 900 μm) to a second pitch (e.g., a coated fiber diameter of 250 μm). A polymeric material encapsulates the optical fibers in the transition segment, and the assembly further includes multiple optical fiber legs each terminated with a fiber optic connector. Optical fibers extending beyond a boundary of the polymeric material are subject to being mass fusion spliced to another group of multiple optical fibers, and the fusion splices encapsulated with polymeric material, to form a fiber optic cable assembly. Methods for fabricating multi-fiber assemblies providing fan-out functionality are further provided, and the need for furcation tubes is avoided.