Initial-boundary value problems on a half-strip with different types of boundary conditions for the generalized Kawahara–Zakharov–Kuznetsov equation with nonlinearity of higher order are considered. In particular nonlinearity can be quadratic and cubic. Results on global existence and uniqueness in classes of weak and strong solutions and large-time decay of small solutions are established. The solutions are considered in weighted at infinity Sobolev spaces. The use of weighted spaces is crucial for the study. To this end new interpolating inequalities in weighted anisotropic Sobolev spaces are established. Both exponential and power weights are admissible. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.