Robertson, a product of the Scone Brumbies, joined the Waratahs academy straight out of school in 2018 and went on to play for the Australian U20s side in 2019.

He made his 1st Grade debut for Sydney Uni as a 20-year-old in the Shute Shield last season, with some impressive performances earning him a wider training squad contract with the Waratahs in 2021.

An injury to Jake Gordon opened the door for Robertson to make his Super Rugby debut this season, coming off the bench against the Brumbies in Round 2, and featured in five games in this year's campaign.

Robertson said he was excited to continue to represent his home state and is determined to work hard and put himself in the frame to wear the Sky-Blue in 2022.

"I'm really grateful for the opportunity to play for the Waratahs and represent NSW," Robertson said.

"Playing for the Waratahs has always been a dream for me and to get the chance earlier this year was a proud moment for myself and my family.

"Playing that first game of Super Rugby made me even more motivated to work hard and put myself in the best position to be able wear the Sky-Blue again next season."

Waratahs Assistant Coach Chris Whitaker was full of praise for his young scrumhalf.

"Robbo is the ultimate team man and a great asset to the Waratahs," Whitaker said.

"His attitude and work ethic are second to none and he is consistently one of our best on the training paddock."

"He got his chance in Super Rugby earlier than we thought he would this season, and he proved he's up to this level.

"I've been really impressed with his development since graduating from our Academy into the main squad.

"Robbo's got a lot of potential and an incredibly bright future here at the Waratahs."

The Waratahs will enter the 2022 season with plenty of depth in the number nine jersey with Robertson joining Jack Grant in shadowing Wallaby scrumhalf Jake Gordon.