[4] Schlossberg and his two older sisters, Rose and Tatiana, were primarily raised in Manhattan's Upper East Side,[5] and have also spent significant time at the Martha's Vineyard estate of their maternal grandmother, the First Lady Jacqueline Bouvier Kennedy Onassis, while growing up.

In eighth grade, he co-founded ReLight New York, a nonprofit organization that installed energy-efficient compact fluorescent lights in low-income housing developments.

[9] A member of the Young Democrats club in high school, he organized a trip to canvass for Barack Obama's campaign in Pennsylvania.

[15] Since 2011, Schlossberg has written for numerous publications and news outlets, including Time, The Washington Post, New York Magazine, Politico, and CNN.

[18] Schlossberg began working for Vogue as a political correspondent in 2024 after graduating from Harvard Law School and passing the bar exam.

[28][29] In the succeeding years, Schlossberg took an increasingly active role in the John F. Kennedy Presidential Library and Museum where he served as chair of the selection committee for the New Frontier Award until its last and 20th ceremony in 2023.

[30][31] Schlossberg has also served as event host, presenter and member of the annual Profile in Courage Award selection committee.

[32][33] In August 2020, Schlossberg gave a virtual address on the second night of the 2020 Democratic National Convention with his mother, Caroline, and endorsed Joe Biden's run for presidency.

[34] In 2023, Schlossberg publicly criticized the presidential campaign of his first cousin once removed, Robert F. Kennedy Jr., and supported Biden’s re-election.

[39] In 2016, Schlossberg attended the Met Gala with his mother Caroline,[40] and was included in the Vanity Fair annual International Best-Dressed List.

[45][46] Months prior to the 2024 U.S. presidential election he began posting political commentary and comedic sketches on social media.

He had publicly opposed his cousin Robert F. Kennedy Jr.'s campaign and later his nomination by President Donald Trump for Secretary of Health and Human Services.

Before leaving social media, he called on his family to denounce RFK Jr. and shared his mother Caroline Kennedy’s statement against the nomination.