It is the first time the UN has given an offensive mandate to its troops.
The 2,500-strong brigade will be asked to "neutralise and disarm" rebels.
The existing 20,000-strong UN peacekeeping force has been widely criticised as ineffective in ending the two-decade long war.
Troops from Tanzania, Malawi, Mozambique and South Africa are expected to form the bulk of the new brigade which is expected to be deployed by July.
The region's mineral riches have been plundered by numerous groups and countries during the long conflict.
The resolution, unanimously adopted by the Security Council,  says the new force will operate "in a robust, highly mobile and versatile manner... to prevent expansion of all armed groups, neutralise these groups, and to disarm them".
The UN's peacekeeping mission has been in DR Congo for more than a decade and was at one time the biggest peacekeeping operation in the world.
It says that their peacekeepers are spread thinly over a vast and difficult terrain.
Last month, regional African leaders signed a UN-brokered accord to end the violence.
Some 500,000 people have fled their homes since a rebellion by M23 rebels began in April last year.
The group is made up of fighters who deserted from the Congolese army following a mutiny and are mostly from the Tutsi ethnic group, a minority in eastern DR Congo.
The UN Security Council has approved the creation of a special combat force to carry out "targeted offensive operations" against armed groups in eastern Democratic Republic of Congo.