In this paper, we explore the monotone Lindelöf property of two kinds of linearly ordered extensions of monotonically Lindelöf generalized ordered spaces. In addition, we construct nonseparable monotonically Lindelöf spaces using the Bernstein set, which generalizes Corollary 4 of Levy and Matveev [‘Some more examples of monotonically Lindelöf and not monotonically Lindelöf spaces’, Topology Appl.154 (2007), 2333–2343].