A cabinet reshuffle has been widely expected since Ramaphosa was re-elected leader of the governing African National Congress (ANC) at a party leadership contest in December, paving the way for him to run for a second term in 2024.
"The president is finalizing his reconfiguration of the national executive," Magwenya said at a news briefing, adding that he was taking into account the swearing in of some members of parliament before announcing the reshuffle.
Ramaphosa is expected to name a new deputy president after the Presidency announced David Mabuza's resignation from the post on Wednesday. The new position of electricity minister is among the roles to be filled.
He announced last month he would create the position of electricity minister to help address the nation's power crisis, as state utility Eskom implements the worst power cuts on record.
The ongoing power crisis has brought criticism upon the South African president as well as lowering the nation's GDP as manufacturing and other sectors have to stop when the power is gone.