Tamoxifen and toremifene are two selective estrogen receptor modulators (SERMs) commonly used to treat breast cancer in women. Toremifene is well‐known as a triphenylethylene derivative. Carboxy toremifene is a common metabolite of toremifene and tamoxifen. Since 2005, the World Anti‐Doping Agency (WADA) has banned the SERMs category during in and out of competition. These substances are in the S4 category in the WADA prohibited list as “agents with anti‐oestrogenic activity.” However, there is no commercially accessible carboxy toremifene reference material in the market. This research highlights the novel synthetic procedure, the development of a carboxy toremifene HPLC method, and validation, along with detailed characterization using advanced analytical techniques using 1H NMR, HRMS, FT‐IR‐ATR and UV–visible spectroscopy. RP‐HPLC‐DAD method was developed and validated to assess the purity of carboxy toremifene. Developed reference material has shown 100% purity. Therefore, we recommend that this synthesized carboxy toremifene may be used as reference material to strengthen the WADA‐accredited lab to maintain a clean sports mission during sports competitions.