The 58-year-old Conrad, who took over the Test team in January 2023, replaces Rob Walter, after he resigned last month for personal reasons, and will be in charge across all formats.
"Coaching the Test side has been the greatest privilege of my cricket journey, and to now oversee the white-ball teams as well is something unbelievably special," Conrad said in a statement from Cricket South Africa.
"South African cricket has incredible white-ball talent. There’s a strong foundation to build on, and I believe we have what it takes to achieve something special."
South Africa will co-host the next 50-over Cricket World Cup in 2027 along with Zimbabwe and Namibia.
A veteran of the domestic coaching circuit, Conrad has enjoyed great success, leading to the WTC final appearance.
South Africa also made the final of last year’s T20 World Cup, but let a commanding position slip as they lost to India, and reached the semi-finals of the 2023 50-over World Cup and the recent ICC Champions Trophy.
Their next limited-overs assignment is a tri-series in Zimbabwe that also involves New Zealand in July. Later in the year, they tour Australia, EnglandEngland and India.