Six Democrats and one independent joined 51 Republicans in voting for Carson to lead the Department of Housing and Urban Development.
Carson has never held public office and has no housing policy experience. But Republicans have praised the life story of a man who grew up in inner-city Detroit with a single mother who had a third-grade education.
When his nomination cleared the Senate Banking, Housing and Urban Affairs Committee in January, Democrats said Carson would not have been their choice, but they welcomed his promises to address lead hazards in housing, homelessness and other issues. He was approved unanimously in the committee.
It also enforces fair housing laws and offers mortgage insurance to poorer Americans through the Federal Housing Administration, part of HUD.
Trump lauded his nominee last week, calling him a "totally brilliant neurosurgeon" who has saved many lives.
"We're going to do great things in our African-American communities," Trump said, appearing with Carson on a tour of the National Museum of African American History and Culture in Washington.