Provision of out of regular business hours (OBH) physiotherapy to hospital inpatients is widespread in the hospital setting. This systematic review evaluated the effect of additional OBH physiotherapy services on patient length of stay (LOS), pulmonary complications, discharge destination, discharge mobility status, quality of life, cost saving, adverse events, and mortality compared with physiotherapy only within regular business hours. A literature search was completed on databases with citation tracking using key words. Two reviewers completed data extraction and quality assessment independently by using modified scales for historical cohorts and case control studies as well as the PEDro scale for randomized controlled trials and quasi-randomised controlled trials. This search identified nine articles of low to medium quality. Four reported a significant reduction in LOS associated with additional OBH physiotherapy, with two articles reporting overall significance and two reporting only for specific subgroups. Two studies reported significant reduction in pulmonary complications for two different patient groups in an intensive care unit (ICU) with additional OBH physiotherapy. Three studies accounted for discharge destination and/or discharge mobility status with no significant difference reported. Quality of life, adverse events, and mortality were not reported in any studies. Cost savings were considered in three studies, with two reporting a cost saving. This systematic review was unable to conclude that the provision of additional OBH physiotherapy made significant improvement to patient outcomes for all subgroups of inpatients. One study in critical care reported that overnight physiotherapy decreased LOS and reduced pulmonary complications of patients in the ICU. However, the studies in the area of orthopaedics, neurology, postcardiac surgery, and rheumatology, which all considered additional daytime weekend physiotherapy intervention, did not provide strong evidence to indicate effective reduction in patient LOS or improving patient discharge mobility status or discharge destination. Investigation should continue in this area, but future trials should ensure factors such as random allocation, groups equal at baseline, blinded investigators, and proven intervention are included in the study design.