The DFLer, who received about 51 percent of first-choice votes, is the city's first African-American mayor.
He previously was St. Paul's Ward 1 City Council member and a staffer in Gov. Mark Dayton's administration. Carter succeeds Chris Coleman, who is running for Minnesota governor in 2018.
Here's what Carter told MPR News on why he ran for mayor:
"We have more people living here than we have in a generation, more places to catch a game, experience the arts, or just grab a great meal or local beer. I think we have work to do to make sure this is a city that works for everyone, where everyone in every corner of our city knows that they have access to the highest quality of public services possible, and building an economy that works for everyone."