Tuesday evening's vote was 13 to five. It came after one of the bill's eight sponsors, Democrat Patrick Leahy, withdrew an amendment that would have given same-sex couples the same legal protections in immigration questions as heterosexual couples.
Several conservative Republicans said they would pull their support for the immigration bill if this were included.
The committee approved other amendments, including one by Republican Orrin Hatch, raising the number of visas available to highly-skilled foreign workers.
The bill's core purpose is to give 11 million illegal immigrants already in the United States the chance to become legal residents if they meet the bill's conditions.
President Barack Obama has called immigration reform one of his top priorities. He congratulated the Judiciary Committee for its vote, saying it is consistent with common sense reform.
He said no one got everything he wanted in the bill, but said the Senate owes it to the American people to get the best possible result.
voanews.com