This paper analyses five constitutional developments in Central and Eastern Europe that can impact the domestic implementation of the UN Guiding Principles on Business and Human Rights (UNGPs). Using Czechia, Poland and Slovenia as examples, the paper highlights four potential drivers, namely: (1) the process of constitutionalizing human rights; (2) the proliferation of the doctrine of horizontal effect of constitutional rights; (3) the constitutional legitimacy of state intervention in the free market economy; and (4) the mechanism of judicial review. Furthermore, the author underlines the most significant challenge, which is increasing resistance to international norms in some countries, e.g., Poland. The paper concludes that the jurisprudence of the constitutional courts can facilitate the domestic implementation of the UNGPs, particularly Pillars I (State duty to protect human rights) and III (access to remedy).