Background: The Canadian Network for Mood and Anxiety Treatments (CANMAT) last published clinical guidelines for the management of major depressive disorder (MDD) in 2016. Owing to advances in the field, an update was needed to incorporate new evidence and provide new and revised recommendations for the assessment and management of MDD in adults., Methods: CANMAT convened a guidelines editorial group comprised of academic clinicians and patient partners. A systematic literature review was conducted, focusing on systematic reviews and meta-analyses published since the 2016 guidelines. Recommendations were organized by lines of treatment, which were informed by CANMAT-defined levels of evidence and supplemented by clinical support (consisting of expert consensus on safety, tolerability, and feasibility). Drafts were revised based on review by patient partners, expert peer review, and a defined expert consensus process., Results: The updated guidelines comprise eight primary topics, in a question-and-answer format, that map a patient care journey from assessment to selection of evidence-based treatments, prevention of recurrence, and strategies for inadequate response. The guidelines adopt a personalized care approach that emphasizes shared decision-making that reflects the values, preferences, and treatment history of the patient with MDD. Tables provide new and updated recommendations for psychological, pharmacological, lifestyle, complementary and alternative medicine, digital health, and neuromodulation treatments. Caveats and limitations of the evidence are highlighted., Conclusions: The CANMAT 2023 updated guidelines provide evidence-informed recommendations for the management of MDD, in a clinician-friendly format. These updated guidelines emphasize a collaborative, personalized, and systematic management approach that will help optimize outcomes for adults with MDD., Competing Interests: Declaration of Conflicting InterestsThe authors declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Camelia Adams has nothing to disclose. Anees Bahji has nothing to disclose. Serge Beaulieu reports research grants, personal fees, and/or nonfinancial support from Abbvie, Boehringer-Ingelheim, Canadian Institutes for Health Research (CIHR), DiaMentis, Idorsia, Eisai, Janssen, and Otsuka-Lundbeck. Venkat Bhat reports research grants from the American Foundation for Suicide Prevention, AMS, Brain and Behaviour Research Foundation, CIHR, Department of Defense, Eisai, New Frontiers in Research Fund, Novartis, Ontario Ministry of Health, Roche, Royal College of Physicians and Surgeons of Canada, and the University of Toronto. Pierre Blier received research grants and/or personal fees from Abbvie, Allergan, CIHR, Janssen, Lundbeck, Merck, Ontario Brain Institute (OBI), Otsuka, Pfizer, University of Ottawa Medical Research Fund, and VilaNova. Daniel M. Blumberger reports research grants, nonfinancial support, and/or other support from Brain Canada, CIHR, Magventure, National Institutes of Health (NIH), and Welcony Inc. Elisa Brietzke reports research grants from Queen’s University Centre for Neuroscience and the PSI Foundation. Trisha Chakrabarty has nothing to disclose. Dr. André Do reports research grants and/or personal fees from AbbVie, CIHR, Janssen, and Otsuka. Benicio N. Frey has nothing to disclose. Dr. Peter Giacobbe reports research grants from CIHR and salary support from the Academic Scholars Fund, Department of Psychiatry, University of Toronto. David David Gratzer has nothing to disclose. Dr. Sophie Grigoriadis reports personal fees from the Canadian Pharmacists Association, Norton, and UptoDate. Jeffrey Habert reports research grants, personal fees and/or other support from Abbvie, Amgen, Astra-Zeneca, Bausch, Bayer, BMS, Boehringer-Ingelheim, Eisai, Eli-Lilly, Elvium, GSK, HLS, Idorsia, Janssen, Lundbeck, Novartis, Novo-Nordisk, Otsuka, Pfizer, and Valeo. M. Ishrat Husain reports research grants and/or other support from the Centre for Addiction and Mental Health (CAMH) Foundation, CIHR, COMPASS Pathfinder, MindSet Pharma, Psyched Therapeutics, University of Toronto, and Wake Network. Zahinoor Ismail reports personal fees from Lundbeck and Otsuka. Sidney H. Kennedy reports research grants, personal fees and/or other support from Abbott, Abbvie, Boehringer-Ingelheim, Brain Canada, Canada’s Strategy for Patient-Oriented Research (SPOR), CIHR, -, Janssen, Lundbeck, Merck, -, OBI, Otsuka, - Servier, and Sunovion. Raymond W. Lam reports research grants, personal fees and/or other support from AbbVie, Asia-Pacific Economic Cooperation (APEC), Bausch, BC Leading Edge Endowment Fund, Brain Canada, CANMAT, Carnot, CIHR, Grand Challenges Canada, Healthy Minds Canada, Janssen, Lundbeck, Michael Smith Health Research BC, MITACS, Neurotorium, OBI, Otsuka, Pfizer/Viatris, Unity Health, and VGH-UBCH Foundation. Alexander McGirr reports other support from Allergan Canada; he holds a patent 63/193,643 pending. Roger S. McIntyre reports research grants and/or personal fees from Abbvie, Alkermes, Atai Life Sciences, Axsome, Bausch, Biogen, Boehringer Ingelheim, Braxia Scientific Corp., CIHR, Eisai, Global Alliance for Chronic Diseases, Intra-Cellular, Janssen, Kris, Lundbeck, Milken Institute, Mitsubishi Tanabe, National Natural Science Foundation of China, Neumora Therapeutics, Neurocrine, NewBridge Pharmaceuticals, Novo Nordisk, Otsuka, Pfizer, Purdue, Sage, Sanofi, Sunovion, Takeda, and Viatris. Erin E. Michalak reports research grants from the Otsuka-Lundbeck Alliance. Roumen V. Milev reports research grants and/or personal fees from AbbVie, Allergan, Canadian Biomarker Integration Network in Depression (CAN-BIND), CIHR, Eisai, Janssen, KYE, Lallemand, Lundbeck, Neonmind, Nubiyota, OBI, Ontario Mental Health Foundation, Otsuka, and Sunovion. Daniel J. Müller reports research grants or personal fees from CAMH AFP Innovation Fund, CAMH Foundation, CIHR, Novagenic, Nubiyota, and OBI. Sagar V. Parikh is the Medical Director for the National Network of Depression Centers and reports research grants, honoraria and/or personal fees from Aifred, Boehringer Ingelheim, Janssen, Medscape, Mensante, Merck, Myriad/Assurex, Otsuka, and Sage; and private shares in Mensante. Lena S. Quilty has nothing to disclose. Arun V. Ravindran has nothing to disclose. Nisha Ravindran has nothing to disclose. Johanne Renaud has nothing to disclose. Joshua D. Rosenblat reports research grants and/or personal fees from Academic Scholars Award, Allergan, American Psychiatric Association, American Society of Psychopharmacology, Boehringer Ingelheim, Braxia Health (Chief Medical and Scientific Officer of Braxia Scientific; Medical Director of the Canadian Rapid Treatment Centre of Excellence [Braxia Health]), Brain and Cognition Discovery Foundation, Canadian Cancer Society, Canadian Psychiatric Association, CIHR, COMPASS, iGan, Janssen, Joseph M. West Family Memorial Fund, Labatt Brain Health Network, Lundbeck, Physician Services Inc. (PSI) Foundation, Sunovion, Timeposters Fellowship, University Health Network Centre for Mental Health, and University of Toronto. Zainab Samaan has nothing to disclose. Gayatri Saraf has nothing to disclose. Kathryn Schade has nothing to disclose. Ayal Schaffer reports personal fees from AbbVie, Lundbeck, and Otsuka. Mark Sinyor has nothing to disclose. Claudio N. Soares reports research grants and/or personal fees from Bayer, Boehinger-Ingelheim, Clairvoyant Therapeutics, Diamond Therapeutics, Eisai, OBI, and Otsuka, Jennifer Swainson reports personal fees, nonfinancial support, and/or other support from AbbVie, Bausch, Eisai, Idorsia, Janssen, Lundbeck, Newly Institute, and Otsuka. Valerie H. Taylor has nothing to disclose. Smadar V. Tourjman reports personal fees from AbbVie, Elvium, Esai, Idorsia, Janssen, Lundbeck, Otsuka, Pfizer, Sunovion, and Takeda. Rudolf Uher has nothing to disclose. Michael van Ameringen reports research grants, personal fees, and/or other support from Abbvie, Bausch Health, Biohaven, Boehringer Ingelheim, CIHR, Elvium (Purdue), Jazz, Lundbeck, Michael G. DeGroote Centre for Medicinal Cannabis Research, Otsuka, Sunovion, Takeda, UptoDate, and Vistagen. Gustavo Vazquez reports personal fees for Abbvie, Allergan, Asofarma, Elea/Phoenix, Eurofarma, Gador, Janssen, Lundbeck/Otsuka, NeonMind Biosciences, Psicofarma, Raffo, Sunovion, and Tecnofarma. Simone Vigod reports royalties from UpToDate. Daphne Voineskos holds the Labatt Family Professorship in Depression Biology, a University Named Professorship at the University of Toronto; she reports research grants from CIHR, CAMH, Centre for Mental Health at University Health Network, Department of Psychiatry at the University of Toronto, and the National Institute of Mental Health. Lakshmi N. Yatham reports research grants and/or personal fees from Abbvie, Alkermes, Allergan, Dainippon Sumitomo, Gedeon Richter, GSK, Intracellular Therapies, Merck, Sanofi, and Sunovion.