They now fill the remaining two vacancies on the seven-member board.
Ahead of the vote, Republicans and Democrats hailed the confirmation vote as a welcome continuation of bipartisanship in the Senate.
The nominees had previously been held up by Sen. David VitterDavid VitterFed chairwoman blasts Trump on debt Senate campaign posts private conversation on Facebook Rand Paul endorses in La. Senate race MORE (R-La.) who objected to an attempt by Senate Majority Leader Harry ReidHarry ReidHispanic Caucus PAC looks to flex its muscles in 2016 Say NO to PROMESA, say NO to Washington overreach Overnight Finance: Wall Street awaits Brexit result | Clinton touts biz support | New threat to Puerto Rico bill? | Dodd, Frank hit back MORE (D-Nev.) to confirm Stein and Powell by unanimous consent. Reid was able to bring the nominees up for a vote by allowing two hours of debate on the nominees.
Vitter disagreed with the nominations, saying he was afraid they would merely "rubber-stamp" monetary policies pushed by Fed Chairman Ben Bernanke. The Fed's recent efforts to boost the economy with low interest rates and expanded balance sheets has attracted GOP criticism from lawmakers who worry the easy-money policies could encourage inflation.
"It would shift the outcome to the left, if you will, it would make it much more likely that the fed would act sooner to bail out megabucks with taxpayer funds," Vitter said. "These two nominees are fine, decent men. They're smart, they're qualified in the professional sense. However, they clearly also support the current direction of Chairman Bernanke and the Fed, and for that reason, I cannot support the nominations and I have real concerns."
Other senators praised how Stein and Powell were confirmed. Sen. Lamar AlexanderLamar AlexanderBipartisan gun measure survives test vote Overnight Healthcare: GOP plan marks new phase in ObamaCare fight Stoddard: The great Trump rebellion MORE (R-Tenn.) noted that though some Republicans opposed the nominations of Stein, a Democrat, and Powell, a Republican, they were still were allowing the confirmations to come up for a vote.
"I am here today not only to say that I admire the nominees — I know one of them well, Jay Powell, who was undersecretary of the Treasury for the first president Bush in an administration in which I served, he has a fine reputation, he should be a fine member," Alexander said. "But I want to acknowledge the fact that the president chose to break the stalemate by nominating a Republican as well as a Democrat.
"And I want to acknowledge the fact that several of my Republican colleagues who have deep concerns of the actions of the Federal Reserve Board during this economic crisis have foregone some of their rights to allow us to have an up-or-down vote at noon."
—Updated at 12:57 p.m.