In this article, we are concerned with the Lagrange stabilisation problem for phase-controlled systems with parameter uncertainties. By using the Kalman-Yakubovich-Popov lemma, the frequency-domain conditions for Lagrange stability of nominal phase-controlled systems are converted into linear matrix inequality (LMI) conditions. The allowable parameter uncertainty bounds for controllability and observability, as well as LMI conditions for Lagrange stability of uncertain phase-controlled systems, are presented. A controller design strategy based on the LMI method is proposed such that the uncertain phase-controlled systems are Lagrange stabilised. A numerical example is provided to demonstrate the effectiveness of the proposed results.