Medine was born on December 20, 1988 in Manhattan. Her father Mois Medine is of Turkish-Jewish descent, and her mother Lyora “Laura” Medine is of Iranian-Jewish descent. She grew up in an Orthodox Jewish household.

Medine’s first foray into online writing began in 2009, while a student at the New School. After studying abroad in Paris, Medine started a blog called Four Months in Paris using the hosting service Blogger. She later renamed it to Boogers and Bagels (stylized as Boogers + Bagels).

The blog primarily covered fashion trends, humor, personal stories, and feminist issues. Its final post was published on April 19, 2010, shortly after the launch of Medine’s second, and better known, blog, the Man Repeller.

Medine started the Man Repeller blog in May 2010 as a hobby. The idea for the blog came during a trip to Topshop with friend Rachel Strugatz, now an online editor at Women’s Wear Daily. Medine recalled, “We were laughing at how everything was so man-repelling: acid-washed harem pants and enormous shoulder pads, and I just said, ‘That’s it! That’s the blog.'”

Medine attended the Ramaz School in Manhattan. She earned a bachelor’s degree in journalism from the New School’s Eugene Lang College in May 2011.

In December 2011 Medine announced her engagement to Abie J. Cohen, a financial advisor at the Swiss investment bank UBS, whom she had met when she was 17 years old. Following the announcement, many responded negatively, questioning her commitment to the principles of “man repelling” outlined in her blog. The Huffington Post wrote: “What happens when the Man Repeller no longer repels men?” In her book Medine outlines her doubts that followed the backlash to her engagement.

In 2012 Medine signed with the Creative Artists Agency, an entertainment talent agency headquartered in Los Angeles, California. In 2016 Medine launched MR by Man Repeller, a line of loafers, flats, metallic booties, and heels exclusive to Net-a-Porter which embodied her not too serious and irreverent style. MR by Man Repeller was followed by Medine’s eponymous shoe brand Leandra Medine, which is sold at Barneys NY, Harvey Nichols, and The Webster.

She and Cohen were wed in June 2012. They live in the East Village. In a December 6, 2016, ManRepeller article, Medine revealed she had suffered a miscarriage. In the December 16, 2016, episode of her podcast, she gave more details about the experience.

In its early years, the blog solely consisted of Medine. Now, there are now 14 employees that edit, write, and promote the website. The blog also covers current events, lifestyle, and feminism. In September 2013 Grand Central Publishing published her book Man Repeller: Seeking Love. Finding Overalls.

In 2013 her brother Haim launched the jewelry line Khai Khai and her mother Laura launched the jewelry line The Laura Medine Collection.

On March 1, 2018, Medine gave birth to twin girls, Laura and Madeline.

On October 29, 2019, Medine launched her partnership collection with Mango.

Medine announced in June 2020 that she would “step back” her involvement in Man Repeller after allegations emerged that she had failed former staffers of colour. In September 2020, the site was rebranded to Repeller and Medine is still listed as the founder on the contributor page. On Oct. 22, Cohen confirmed that Repeller will be shutting down due to financial constraints.