Joining hooker Marx were props Ox Nche and Thomas du Toit, twice Player of the Year Pieter-Steph du Toit, flyhalf Sacha Feinberg-Mngomezulu and winger Cheslin Kolbe, a year after seven Springboks were named in the 2024 list.
"I'd like to extend a heartfelt congratulations to Malcolm, Pieter-Steph, Ox, Thomas, Sacha and Cheslin on behalf of SA Rugby and the entire country for being named in the Dream Team," said Mr Alexander.
"They have all played exceptionally well this season and deserve this honour. Being named in this team is a massive achievement, especially since it consists of the best players throughout the world.
"To see six Springboks included is a testament to the quality of players we have in South Africa."
Alexander said the springboks were a great symbol of South Africa's unity when working towards a common goal.
"The Springboks are a true symbol of what we can achieve as a country and as a team when everyone works together," he said. "It is a brotherhood more than anything else and I'd like to congratulate coach Rassie Erasmus, his coaching staff and management team for ensuring that the players remain the best version of themselves on and off the field."
South Africa capped off a highly successful year by securing back-to-back Rugby Championship titles for the first time.
New Zealand, Australia and England each contributed two players to the Dream Team.
WORLD RUGBY MEN'S 15s DREAM TEAM OF THE YEAR 2025
Ox Nche (South Africa)
Malcolm Marx (South Africa)
Thomas du Toit (South Africa)
Maro Itoje (England)
Pieter-Steph du Toit (South Africa)
Tom Curry (England)
Harry Wilson (Australia)
Cam Roigard (New Zealand)
Sacha Feinberg-Mngomezulu (South Africa)
Louis Bielle-Biarrey (France)
Len Ikitau (Australia)
Cheslin Kolbe (South Africa)
Will Jordan (New Zealand)