All 50 Republican senators, plus eight Democrats, backed Mr Ashcroft, handing President George W Bush a victory in his first battle with congressional opponents.
All 50 Republican senators, plus eight Democrats, backed Mr Ashcroft, handing President George W Bush a victory in his first battle with congressional opponents.
Mr Ashcroft, 58, pledged during his confirmation hearings to enforce all of the nation's laws, even though he opposes abortion rights, gay rights and gun control.
A final vote tally was delayed in the Senate - split 50-50 between Republicans and Democrats - until Senator Joseph Biden had returned from a funeral.
He had earlier said, however, that he would join the 41 other Democratic senators in opposing Mr Ashcroft's nomination.
Correspondents say the Democrat stance on the issue is intended to send a clear signal to President Bush that they will resist the nomination of conservative judges.
The vote ended the bitterest fight for any of Mr Bush's cabinet nominees.
"We hope nominees for sensitive positions come from the centre not from the far right," he said.
But assistant Republican leader Don Nickles accused Mr Ashcroft's enemies of unfairly depicting him as an extremist.
"I have absolute, total, complete confidence he is going to be one outstanding attorney-general," he told reporters.
Mr Ashcroft was twice governor of Missouri and once state attorney-general.
He lost his bid for re-election to the Senate in a race against the late Democrat Governor, Mel Carnahan, who died in an air crash shortly before votes were cast. Mr Carnahan's widow is taking over his seat.
One to go
Only one more Bush nominee now remains to be confirmed.
Robert Zoellick is expected to be approved as trade representative when senators vote next Tuesday.
Two days ago, the Senate confirmed President Bush's choices for the country's two top environmental posts.
Environmentalists had objected strongly to the nomination of one, Gail Norton, as secretary of the interior, but she was confirmed by a vote of 75 to 24 with one abstention.
Former New Jersey Governor Christine Todd Whitman won unanimous approval to head the Environmental Protection Agency.