Introduction: The health, economic, and social burden caused by mental disorders has helped make mental health a top public health priority. The objective of this study is to present prevalence data on major depressive episodes (MDEs) in mainland France in 2017, to identify the most affected population segments, and to observe trends since 2005.Method: In 2017, the Health Barometer surveyed 25,319 people aged 18 to 75 via telephone and computer-assisted data collection using a random sample. CDE was measured using the Composite International Diagnostic Interview-Short Form (CIDI-SF).Results: Nearly one in ten people had experienced EDC in the past 12 months. Women, particularly those aged 35–44, people under 45, the unemployed and other economically inactive individuals, widowed or divorced people, and those reporting low incomes had the highest prevalence rates. After remaining stable between 2005 and 2010, the prevalence of major depressive disorder increased by 1.8 percentage points over the 2010–2017 period; this increase was more pronounced among women (+3 percentage points), those aged 35–44 (+4 percentage points), the unemployed (+5 percentage points), and individuals reporting low income (+3 percentage points). Discussion: The high prevalence of depression, as well as its increase in recent years, calls for strengthening measures for the prevention and management of depressive disorders, particularly for the most vulnerable populations.