The 51-year-old helped lead the Springboks to back-to-back Rugby World Cups in 2019 and 2023.
Erasmus, who was head coach for the 2019 victory, had been in a director of rugby role for the recent tournament in France.
“I will be more hands-on at the field sessions,” Erasmus said.
“In my role as director of rugby in the last four years I continued to oversee the team structures and strategy in conjunction with Jacques and the other coaches, so it should be an easy transition back into the head coach role.”
Harlequins defence coach Jerry Flannery will depart his role this month to take charge of the world champions’ defence.
South Africa’s former defence coach Felix Jones, who was also part of both World Cup wins, joined England after the World Cup.
In further additions, former New Zealand fly-half Tony Brown joins as attack coach and Duane Vermeulen, who started both World Cup finals, is named in a roving coaching role.
The former number eight will be involved with all South Africa’s national teams, joining forces with existing coaches, Franzel September and Bafana Nhleko.
Recently retired international referee Jaco Peyper also joins as national laws adviser.
