Abstract Background Multiple short delirium detection tools have been validated in research studies and implemented in routine care, but there has been little study of these tools in real‐world conditions. This systematic review synthesized literature reporting completion rates and/or delirium positive score rates of detection tools in large clinical populations in general hospital settings. Methods PROSPERO (CRD42022385166). Medline, Embase, PsycINFO, CINAHL, and gray literature were searched from 1980 to December 31, 2022. Included studies or audit reports used a validated delirium detection tool performed directly with the patient as part of routine care in large clinical populations ( n ≥ 1000) within a general acute hospital setting. Narrative synthesis was performed. Results Twenty‐two research studies and four audit reports were included. Tools used alone or in combination were the Confusion Assessment Method (CAM), 4 ‘A's Test (4AT), Delirium Observation Screening Scale (DOSS), Brief CAM (bCAM), Nursing Delirium Screening Scale (NuDESC), and Intensive Care Delirium Screening Checklist (ICDSC). Populations and settings varied and tools were used at different stages and frequencies in the patient journey, including on admission only; inpatient, daily or more frequently; on admission and as inpatient; inpatient post‐operatively. Tool completion rates ranged from 19% to 100%. Admission positive score rates ranged from: CAM 8%–51%; 4AT 13%–20%. Inpatient positive score rates ranged from: CAM 2%–20%, DOSS 6%–42%, and NuDESC 5–13%. Postoperative positive score rates were 21% and 28% (4AT). All but two studies had moderate–high risk of bias. Conclusions This systematic review of delirium detection tool implementation in large acute patient populations found clinically important variability in tool completion rates, and in delirium positive score rates relative to expected delirium prevalence. This study highlights a need for greater reporting and analysis of relevant healthcare systems data. This is vital to advance understanding of effective delirium detection in routine care.