A jacketed light emitting diode assembly is provided, which includes a light emitting diode including a set of positive and negative contacts, and a lens body containing a semiconductor chip and end portions of the contacts. An electrical wire set of first and second electrical wires are connected to the positive contact and the negative contact, respectively. A light transmissive cover receives the lens body, and has an opening through which at least one of the contact set and the electrical wire set passes. An integrally molded plastic jacket at the opening of the light transmissive cover provides a seal at the opening against moisture and airborne contaminants. A waterproof light string including one or more of the jacketed light emitting diode assemblies is also provided, as are related methods.