BackgroundThe integrated motivational-volitional model (IMV) is one of the leading theoretical models of suicidal thoughts and behavior. There has been a recent proliferation in the assessment of suicidal and nonsuicidal self-harm thoughts and behaviors (SHTBs) in daily life. ObjectiveThis systematic review synthesized evidence from ecological momentary assessment (EMA) studies in the SHTB literature to address the following questions: (1) Which constructs in the IMV model have been assessed using EMA, and how have they been assessed? (2) Do different constructs from the IMV model fluctuate in daily life? (3) What is the relationship between the different IMV constructs and SHTBs in daily life? MethodsConsistent with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we conducted systematic searches of 5 databases—Web of Science, Embase, MEDLINE, PsycINFO, and Europe PMC Preprints—from inception to March 26, 2024. ResultsOur searches resulted in the inclusion and narrative synthesis of 53 studies across 58 papers. A total of 15 IMV constructs were measured using EMA across the included papers. The most frequently measured constructs were thwarted belongingness (24/58, 41% of the papers), future thinking (20/58, 34% of the papers), and perceived burdensomeness (16/58, 28% of the papers). The least frequently measured constructs were humiliation, social problem-solving, mental imagery, and perceived capability for suicide. None of the included papers measured memory biases, goals, norms, or resilience using EMA. Comparison of intraclass correlation coefficients (45/58, 78% of the papers) revealed moderate but inconsistent within-person variance across all the examined constructs. We found evidence (39/58, 67% of the papers) of concurrent associations between almost all constructs and SHTBs in daily life, with some evidence that entrapment, shame, rumination, thwarted belongingness, hopelessness, social support, and impulsivity are additionally associated with SHTBs in lagged (ie, longitudinal) relationships. ConclusionsComparisons were hindered by variation in methodology, including the populations studied, EMA sampling scheme, operationalization of IMV constructs and SHTBs, and statistical approach used. Our findings suggest that EMA studies are a useful methodology for examining risk factors for SHTBs; however, more research is needed for some IMV constructs. Quality assessment suggested several areas for improvement in the reporting of EMA studies in this field. Trial RegistrationPROSPERO CRD42022349514; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=349514