The present application provides a sublimation ink which is capable of being transferred to natural fiber fabrics, such as cotton and linen, in addition to synthetic fabrics, such as polyester, nylon, etc., and shows significantly improved color fastness. The sublimation ink may include a resin containing at least one active hydrogen, a crosslinking agent having at least two isocyanate (—NCO) groups, and one or more colorants. The sublimation ink may also include one or more carriers, binders, thickeners, and/or solvents. An image can be printed on a transfer medium (e.g. paper) at room temperature with the sublimation ink using conventional offset printer so that the sublimation ink remains inactive. The image can be subsequently transferred onto any desired fabrics under heat and pressure, in which the sublimation ink is activated and bonds the colorant to the fabrics with excellent color effect.