BACKGROUND: Smartphone applications could improve symptoms of borderline personality disorder (BPD) in a scalable and resource-efficient manner in the context limited access to specialized care. OBJECTIVE: This systematic review and meta-analysis aims to evaluate the effectiveness of applications designed as treatment interventions for adults with symptoms such as anger, suicidality, or self-harm that commonly occur in BPD. DATA SOURCES: Search terms for BPD symptoms, smartphone applications, and treatment interventions were combined on PubMed, MEDLINE, and PsycINFO from database inception to December 2019. STUDY SELECTION: Controlled and uncontrolled studies of smartphone interventions for adult participants with symptoms such as anger, suicidality, or self-harm that commonly occur in BPD were included. STUDY APPRAISAL AND SYNTHESIS METHODS: was used to compute between-groups effect sizes in controlled designs. The primary outcome was BPD-related symptoms such as anger, suicidality, and impulsivity; and the secondary outcome was general psychopathology. An average dropout rate across interventions was computed. Study quality, target audiences, therapeutic approach and targets, effectiveness, intended use, usability metrics, availability on market, and downloads were assessed qualitatively from the papers and through internet search. RESULTS: Twelve studies of 10 applications were included, reporting data from 408 participants. Between-groups meta-analyses of RCTs revealed no significant effect of smartphone applications above and beyond in-person treatments or a waitlist on BPD symptoms (Hedges'  = - 0.066, 95% CI [-.257, .125]), nor on general psychopathology (Hedges'  = 0.305, 95% CI [- 0.14, 0.75]). Across the 12 trials, dropout rates ranged from 0 to 56.7% ( = 22.5, 95% CI [0.15, 0.46]). A majority of interventions studied targeted emotion dysregulation and behavioral dyscontrol symptoms. Half of the applications are commercially available. CONCLUSIONS: The effects of smartphone interventions on symptoms of BPD are unclear and there is currently a lack of evidence for their effectiveness. More research is needed to build on these preliminary findings in BPD to investigate both positive and adverse effects of smartphone applications and identify the role these technologies may provide in expanding mental healthcare resources.