O, The Oprah Magazine, sometimes simply abbreviated to O, is a monthly magazine founded by Oprah Winfrey and Hearst Communications, primarily marketed at women.

It was first published on April 19, 2000. As of June 2004, its average paid circulation was over 2.7 million copies, two thirds by subscription. A South African edition was first published in April 2002; according to the South African Advertising Research Foundation, its average readership was over 300,000. The editor of the South African edition is Samantha Page.^[2] While most US magazine sales declined in 2009, O Magazine increased its newsstand sales by 5.8 percent to 662,304 copies during the second half of the year.^[3] The magazine's newsstand sales fell 15.8% during the first half of 2010,^[4] while its subscription circulation increased,^[5] and sales fell 8.2% in the later half of the year.^[6]

Since its inception, Oprah has appeared on the cover of each issue. The first shared cover is her April 2009 issue in which she appears with the First Lady Michelle Obama.^[7] The second shared cover is with fellow daytime host Ellen DeGeneres on the December 2009 issue. Four separate covers were shot for this special holiday issue.^[8] The December issue of O hit newsstands on November 12, 2009.^[9] O, the Oprah Magazine serves 63.6% Caucasian, 29.8% African-American, 8.8% Hispanic, 1.8% Asian and 6.6% other women. It is directed towards a median age of 47.9, median home value of $214,281, median HHI of $68,911, and median IEI of $38,756.^[10]

The mission statement of O Magazine presented by O Media Kit^[11] is to "Live Your Best Life". They also stated in their mission statement, "As the only magazine devoted to personal growth, O, The Oprah Magazine engages and addresses every aspect of a woman's life - from beauty and style, to food, health, and more. We inspire, motivate and celebrate our reader's journeys to live their best life."^[12]

The December 2010 issue of The Oprah Magazine^[13] was the first released digitally through the magazine's app for the iPad.^[14] The app features exclusive videos of Oprah, allows readers to preview and purchase books presented in the magazine's Reading Room and O List sections, and gives users the ability to purchase monthly or yearly subscriptions. Individual issues are also available for download through the app.^[15]

In July 2009, Susan Casey became the editor-in-chief of the magazine. Before joining, she was the development editor of Time Inc.. Casey was editor-in-chief of Sports Illustrated Women, editor-at-large for Time Inc., and creative director of Outside. Casey wrote The New York Times bestseller The Devil's Teeth: A True Story of Obsession and Survival Among America's Great White Sharks, and The Wave.

In September 2009, the magazine hired former Publishers Weekly editor–in–chief Sara Nelson as books editor at O.^[16][17][18]

In May 2013, Lucy Kaylin was promoted to editor-in-chief, replacing Susan Casey.^[19]

In 2015, the magazine teamed up with Flatiron Books of St. Martin's Press and published a series of inspiration books, including O's Little Book of Happiness and, in 2016, O's Little Book of Love & Friendship.

In a March 2001 an article entitled O Positive, Noreen O'Leary argued that Winfrey was well on her way to influencing the content of women's magazines beyond her own, just as she has helped reshape daytime TV and the world of book publishing.^[20]

In April 2001, Oprah Winfrey and the Hearst Corporation were sued for trademark infringement by Ronald Brockmeyer, the publisher of «O» Magazine, a German erotic periodical which predated Winfrey's magazine by several years. In a March 2003 decision, Judge John Koeltl dismissed the suit, citing the different content of the two magazines and the irregular publication schedule and minimal American sales of the German magazine.