Although theoretical models have highlighted the close relation between long-term memory (LTM) and attention, we have little understanding of how the processes of orienting, selecting, and prioritising relevant contents in long-term memory unfold. Here we build on findings and methods developed to study internal selective attention in working memory (WM), to show that selection and prioritisation of contents from long-term memory improves recall of stored information and guides perception in a secondary task. We developed a task in which participants hold separate colour-location combinations in LTM and WM. Subsequently, a colour cue (‘retro-cue’) would indicate the identity of the target that would be probed in a memory recall task after a short delay. Critically, in half of the trials, following the delay participants would instead have to complete a perceptual detection task in which stimuli unrelated to memory contents briefly flash on the screen. Our results show that selection and prioritisation of contents from both long-term and working memory not only improve memory recall, but also enhance perceptual sensitivity when the probed location in the perception task is matched with the currently prioritised location in LTM/WM. Our method of studying internal selective attention in long-term memory opens the door to exploring our flexible and adaptive usage of memories in service of behaviour.We reported how working memory (WM) and long-term memory (LTM) traces can guide external spatial attention when retro-cued before a perception task, and how timing has a critical influence on the guidance from WM and LTM.