Mezvinsky is a son of former Pennsylvania Rep. Marjorie Margolies-Mezvinsky and former Iowa Rep. Ed Mezvinsky, longtime friends of the Clintons. Ed Mezvinsky was released from federal prison last year after serving a nearly five-year sentence for wire and bank fraud.
Margolies-Mezvinsky served just one term in Congress before losing her seat in 1994 after voting in favor of President Clinton's 1993 budget, which was controversial at the time.
The former first daughter and her fiancé became friends as teenagers in Washington and both attended Stanford University. They now live in New York, where Mezvinsky works at G3 Capital, a Manhattan hedge fund, and Clinton is pursuing a graduate degree at Columbia University's School of Public Health.
Before returning to graduate school, Clinton worked at Avenue Capital, a hedge fund run by prominent Democratic donor Marc Lasry. She also worked at McKinsey and Company, a management consulting firm.
Since her debut on the public stage as a curly haired 12-year old during her father's 1992 presidential campaign, Clinton has maintained a fairly low public profile. That changed in 2008, when the press-shy Clinton stepped out on the campaign trail to help her mother's bid for the Democratic presidential nomination.
Before beginning a relationship with Mezvinsky, Clinton dated Ian Klaus, a Rhodes Scholar she met while studying international relations at Oxford in 2002. Klaus dedicated his first book, "Elvis is Titanic," about his experience teaching in the Kurdistan province of Iraq, to Clinton.
Earlier this year, Hillary Clinton was forced to tamp down speculation that her daughter and Mezvinsky were already engaged and would marry in August on Martha's Vineyard. President Obama, who was vacationing on the island at the time, was rumored to be on the guest list.
Clinton aides, citing Chelsea's privacy, declined to disclose whether she has received an engagement ring or any other details about wedding plans. It will be an interfaith marriage; Mezvinsky is Jewish, while Clinton grew up attending Methodist Church with her mother. Bill Clinton is Southern Baptist.
Word of the engagement was first reported by ABC News.