Pixelated-LED chips including a plurality of independently electrically accessible active layer portions supported by a plurality of discontinuous substrate portions to form a plurality of pixels, with underfill material of varying composition provided between sidewalls of adjacent pixels. Underfill materials having different reflection, scattering, absorption, filtering, etch-resistance, and/or light refraction properties may be provided in multiple layers. A method for fabricating a pixelated-LED chip includes defining streets through an active layer and portions of a substrate to form active layer portions, thinning an entire upper portion of a substrate to create openings into the streets and form discontinuous substrate portions bounding the streets, and supplying underfill material through the openings into the streets.