Valetini, who has played six Super Rugby matches for the Brumbies claiming two tries, has excited rugby fans throughout Australia with his swashbuckling performances for the ACT side, combining power and pace to great effect to become a firm fans favourite.
The young flanker most recently crossed for a well-taken try in the match against the Rebels at AAMI Park in Melbourne and will likely be a mainstay of the Brumbies pack over the next three years.
"I am very pleased to have extended my contract at the Brumbies for a further two seasons," Valetini told the Brumbies' official website.
"It was an easy decision for me in the end as I have loved every minute of my time here at the club. I feel like I am learning every day off a fantastic group of players and our coaching staff.
"Dan, Peter and Laurie have shown great faith in me and my ability and I am looking forward to continuing to improve as a player under their coaching. I really enjoy playing in Canberra in front of our loyal and passionate fans and am excited by the future ahead of us."
Valetini made his Brumbies debut in Tokyo in Round One last year, becoming Brumby number 199 when he began his maiden Super Rugby match for the club and crossing for his first try in Brumbies colours against the Rebels at GIO Stadium in Round 13.
"Rob showed on Friday night what he was capable of against the Rebels where I think he was our best player," Brumbies head coach Dan McKellar commented.
"He's very new to Super Rugby and the professional environment, but the potential for Rob to kick on and become a dominant player at club and international level is certainly there and we are pleased to have him around for a few more years."
Amongst his many attributes, Valetini is solid in both attack and defence and he brings a multitude of assets to the Brumbies line-up according to McKellar.
"His ball-carry stands out," he said. "He is a big body and is aggressive and he likes to take on the defensive line. He has got the ability to bend the line which is rare in this day and age, but it's his work rate, his repeat efforts in both attack and defence that stand out.
"We took him on as a seventeen-year-old and that says a lot about his character that he was prepared to move away from home to become the best player he can be. He still has a lot of developing to do on field and off field, with understanding of what it takes to be a truly professional footballer but it's all ahead of him."