Mild traumatic brain injury (mTBI) is common in children aged < 5 years, however, less is known about their experience of post-concussive signs and symptoms. This systematic review aims to identify post-concussive signs and symptoms experienced by preschool children up to 12 months post-injury, and to review the methods used to report this data. Relevant findings, including rates, progression, and possible predictors of post-concussive signs and symptoms were also identified. Databases (Ovid MEDLINE, EMBASE, PsycInfo, PubMed, Scopus) and reference lists were searched for relevant articles, which were screened based on specified criteria. Eleven articles met the inclusion criteria, being original studies published in English and presenting data on post-concussive signs and symptoms specific to preschool children with mTBI. Most reviewed studies investigated acute presentations of mTBI, and identified that preschool children demonstrate post-concussive symptoms (PCS) similar to other age groups. Post-traumatic amnesia duration of approximately one day was reported in preschool children following mTBI, as were changes in mood and behavior during the recovery period. Parents were the main informants, with data obtained through either interview or questionnaire. Review findings highlight the lack of empirical data regarding the presentation and progression of PCS in preschoolers following mTBI and evidence on how to best manage this group during recovery.