In his short representative career, Roets has already rubbed shoulders with All Blacks legend Dan Carter and Springboks utility back Johan Goosen when he was recruited by French club Racing 92 for the 2016/2017 academy season.
The 23-year-old has played age grade rugby in South Africa and in the Currie Cup competition for the Lions, Bulls and Pumas.
Waratahs head coach Daryl Gibson said Roets brings size and skill to the forwards.
“We first noticed his talent in the Currie Cup and we have been searching for a big, aggressive and physical player who can get us going forward and excels in the set piece,” Gibson told the Waratahs’ official website.
“At 135kg, Le Roux fits the profile that we have been wanting to add to our squad. His recruitment will add real competition and depth amongst our current lock options in Rob Simmons, Tom Staniforth, Ryan McCauley and Jed Holloway.”
Roets said he was buoyed by the opportunity to play for the 2018 Super Rugby semi-finalists.
“My goal was to be selected for a Super Rugby team and to have the chance to play for the New South Wales Waratahs is amazing,” he said.
“This is a team that has won a championship title and in watching them play in 2018, I cannot wait to be part of them doing even better this year.”