The Senate approved the general's nomination Thursday as part of a package of nominees approved by voice vote before senators began their monthlong August recess, The Hill reported.
The Senate also approved Joint Chiefs Vice Chairman Adm. James Winnefeld.
Dempsey's confirmation breezed through both the Senate Armed Services Committee and full Senate this week, but not before he faced pushback from Sen. John McCain, R-Ariz.
McCain and Dempsey got into a heated exchange during Dempsey's confirmation hearing last month, when the senator pressed Dempsey for his personal opinion on U.S. military intervention in Syria. After Dempsey declined, McCain threatened to place a hold on Dempsey's confirmation.
Senate Armed Services Chairman Carl Levin, D-Mich., requested Dempsey to submit an assessment of military options and their costs and benefits. Once he did so, McCain backed off his threat.
In a statement after Dempsey's confirmation McCain said he still was "seriously concerned about the advice that our nation's top military leaders have given the president and National Security Council regarding the most serious and time-sensitive crises in the world today."