Polyethers like poly(ethylene glycol) have been widely used for a variety of valuable applications, although their functionalization still poses challenges due to the absence of functional handles along the polymer backbone. Herein, a series of novel azide-functionalized glycidyl ether monomers are presented as a universal approach to synthesize functional polyethers by post-polymerization modification. Three azide-functionalized glycidyl ether monomers possessing different alkyl spacers (ethyl, butyl, and hexyl) were designed and synthesized by a simple two-step substitution reaction. Organic superbase-catalyzed anionic ring-opening polymerization can proceed under mild conditions compatible with an azide pendant group, affording well-controlled azide-functionalized polyethers with low dispersity (D < 1.2). The azide pendant groups on the resulting polymers were readily modified to a variety of functional groups via copper-catalyzed azide-alkyne cycloaddition reactions and Staudinger reduction. Furthermore, copolymerization of azidohexyl glycidyl ether with allyl glycidyl ether was demonstrated to provide an additional orthogonal functional handle. We anticipate that this work provides a new platform for the preparation of diverse functional polyethers.