This paper aims to obtain new Karush–Kuhn–Tucker optimality conditions for solutions
to semi-infinite interval equilibrium problems with interval-valued objective functions. The
Karush–Kuhn–Tucker conditions for the semi-infinite interval programming problem are
particular cases of those found in this paper for constrained equilibrium problem.We illustrate
this with some examples. In addition, we obtain solutions to the interval equilibrium problem
in the unconstrained case. The results presented in this paper extend the corresponding results
in the literature.The research has been supported by FEDER Andalucía 2014-2020 (UPO-1381297) and by MICIN through grant MCIN/AEI/PID2021-123051NB-100