Since retiring from playing in 2015, Van Zyl has experience with stints as forwards coach at Free State Cheetahs, London Irish and Ealing Trailfinders.
He had been linked with the head coach role at Benetton, but that position has been filled by former Scarlets and Wales boss Wayne Pivac.
“We have built a strong working relationship this season and I have seen at first-hand the standards Corniel brings and drives every day,” said Cardiff Rugby managing director Jamie Muir.
“It is a significant appointment for the club and one that has the full backing of myself and the board.
“We believe Corniel is the right person to lead our rugby programme and to continue strengthening every aspect of our high-performance environment.”
Muir explained why the appointment had not been made sooner.
“We didn’t want to rush into a decision when Matt Sherratt departed, but we have been impressed with Corniel,” said Muir.
“He brings a different edge to the club, and a competitive mindset combined with calm leadership.
“We are excited about the direction we are heading and are confident, with the guidance and leadership from Corniel and his staff, we can continue building a squad and culture supporters can be proud of.
“This appointment is about long-term progress, stability and ambition and we are looking forward to what comes next.”