The establishment and progressive wings of the party were split between Perez and Minnesota Rep. Keith Ellison over the last several months. Some progressives said they would be reluctant to fall in line behind Perez.
Perez has work to do: In addition to losing the 2016 presidential race, the Democrats have lost dozens of congressional seats and hundreds of state legislature seats over the last several election cycles.
So who is Tom Perez? Here's everything you need to know:
Who is Tom Perez?
Tom Perez served as secretary of labor for three years after being appointed by former President Barack Obama in 2013. Before that, he was labor secretary for the state of Maryland and was a civil rights attorney for the Department of Justice. He's also a graduate of Harvard Law School. Perez was born to Dominican immigrants in Buffalo, New York. He has never held elected office.
How did he get elected?
A group of more than 400 top Democrats gathered on Saturday in Atlanta to cast their ballots to replace interim Chairwoman Donna Brazile. Perez fell one ballot short of a majority on the first round of voting. He defeated Ellison in the second round, 235-200.
Who supported Perez for chairman (and who didn't)?
Perez lined up several high profile endorsements from former President Obama's orbit, including former Vice President Joe Biden, former Attorney General Eric Holder and former Health and Human Services Secretary Kathleen Sebelius. But Senate Minority Leader Chuck Schumer and Sen. Bernie Sanders backed Ellison, and former Chairman Howard Dean backed South Bend, Indiana, Mayor Pete Buttigieg. Obama and former presidential nominee Hillary Clinton did not endorse anyone.
What did Perez do as labor secretary?
Perez's nomination for secretary of labor was divisive. He was confirmed 54-46 on a party-line vote after criticism from Republicans. Those in the Obama administration called him an effective leader and manager. He worked closely on minimum wage issues. But in order to toe the Obama White House line, he backed the controversial Trans-Pacific Partnership trade deal. The decision put him at direct odds with several major unions across the country.
What happens next?
The question now is whether Perez can unite various factions of the party and bring grass-roots organizers into the fold. Perez named Ellison deputy chairman of the party immediately after the vote. Several leading progressive activists, including chairs of the Women's March and founders of the People for Bernie organization, remain skeptical of Perez. They lobbied hard for Ellison and framed the race as an outsider against an insider, creating the perception among many that by electing Perez over Ellison, the party was missing a crucial opportunity reach out and include people who felt left out and on the fridges of the institution.