Waterborne polyester is a common eco‐friendly material in which ester bonds are easy to hydrolyze. Therefore, we synthesized a series of waterborne comb‐like polyesters (WCPEs) with hydrophilic side chains through aza‐Michael addition under green and mild conditions. The physicochemical structure of the polyesters was verified by 1H NMR, FTIR, and GPC characterizations. The pH value of dispersions dropped by less than 0.7 after storage for 2 months. The dispersions remained stable after 6 months at room temperature. In addition, the WCPEs exhibited good wetting and dispersing ability for pigment particles as Tego 740 W, which is a mature pigment dispersant product for waterborne coatings. Moreover, the cross‐linked WCPEs exhibited excellent chemical resistance, there was only 1.2% weight loss, and almost no mechanism properties decline for cross‐linked transparent films even after treatment under an alkaline environment for 20 days. Thus, the synthesized WCPE has potential application as an alkali resistance eco‐friendly material, and possesses excellent performance as pigment‐dispersion resin.