Farrow was born December 19, 1987 in New York City to Actress Mia Farrow and Woody Allen. Now known as Ronan, he originally was named after Hall of Fame baseball pitcher Satchel Paige and Actress Maureen O'Sullivan, his maternal grandmother. He was given the surname "Farrow" to avoid a family with one child named Allen amid Farrows and Previns. In 2013, Mia Farrow raised speculation that singer-actor Frank Sinatra was Farrow's biological Father.
From 2001 to 2009, he was a UNICEF Spokesperson for Youth, acting as an "advocate" for children and women caught up in the ongoing crisis in Sudan's Darfur region and assisting in fundraising and addressing United Nations affiliated groups in the United States. During this time, he also made joint trips to the Darfur region of Sudan with his mother, the Actress Mia Farrow, who is a UNICEF Goodwill Ambassador. He subsequently advocated for the protection of Darfuri refugees. Following on his experiences in Sudan, Farrow was affiliated with the Genocide Intervention Network.
In 2008 Farrow was awarded Refugees International's McCall-Pierpaoli Humanitarian Award for "extraordinary Service to refugees and displaced people." In 2009 Farrow was named New York magazine's "New Activist" of the year and included on its list of individuals "on the verge of changing their worlds." In 2011 Harper's Bazaar listed him as an "up-and-coming politician". In 2012, he was ranked number one in "Law and Policy" on Forbes magazine's "30 Under 30" Most Influential People. He was also awarded an honorary doctorate by Dominican University of California in 2012.
In 2009, Farrow joined the Obama administration as Special Adviser for Humanitarian and NGO Affairs in the Office of the Special Representative for Afghanistan and Pakistan. He was part of a team of officials recruited by the diplomat Richard Holbrooke, for whom Farrow had previously worked as a speechwriter. For the next two years, Farrow was responsible for "overseeing the U.S. Government's relationships with civil society and nongovernmental actors" in Afghanistan and Pakistan.
Farrow voiced minor characters in the English-language versions of two Japanese animated films, From Up on Poppy Hill (2011) and The Wind Rises (2013).
In its 2013 retrospective of men born in its 80 years of publication, Esquire magazine named him the man of the year of his birth.
When asked about longstanding speculation that Farrow is the son of Mia Farrow's ex-husband Frank Sinatra, Mia Farrow stated that Sinatra might "possibly" be his Father. Ronan Farrow subsequently joked on Twitter, "Listen, we're all *possibly* Frank Sinatra's son". In February 2014, Allen replied in The New York Times, writing, "Is he my son or, as Mia suggests, Frank Sinatra's?" In 2015, Vanity Fair asked Nancy Sinatra about Farrow being treated as if he were a member of their family. She answered in an e-mail, "He is a big part of us, and we are blessed to have him in our lives."
DNA paternity testing to determine Farrow's Father is not known to have occurred. In a 2015 CBS Sunday Morning interview, Nancy Sinatra denied that Farrow was her half-brother. Farrow has refused to discuss DNA, and stated, "Woody Allen, legally, ethically, personally was absolutely a Father in our family."
In October 2017, The New Yorker published an investigative article by Farrow, after Farrow's employer, NBC, decided against airing his findings, detailing allegations of sexual misconduct said to have been committed by film Producer Harvey Weinstein.
In April 2018, Farrow came out as part of the LGBT community at an award ceremony, hosted by the Point Foundation.