Signing his first professional contract, the Fosroc Scottish Rugby Academy graduate joins the club having impressed during this year's U20s Six Nations. He featured in four games and crossed the whitewash on three occasions.
With a strong kicking game and quick pace McLean can play across the back three, having started in both positions for Scotland at U20s level.
The 20-year-old, current Strathclyde Sport Scholar, has shone throughout Scottish age grade rugby representing Scotland at U16, U17, U18 and U20 levels and being named in the 12-man Team GB U18 7s squad that took part in the 2018 Youth Olympic Games Qualifying Event in Panevezys, Lithuania.
Welcoming Rufus into his squad Head Coach, Danny Wilson, said: "Rufus is a great young talent. His game has really improved whilst a part of the academy and he was a stand-out player across the back three for Scotland U20s this year.
"His work ethic and drive have really impressed the coaches and we look forward to welcoming him into the senior squad next season."
On the signing of McLean, Scotland U20s head coach Sean Lineen said: "Rufus is such an exciting young Scottish talent.
"He plays with a real maturity in his game and he's taken every new level in his stride.
"His ability to play across the back three - as we saw for Scotland U20 this year - makes him a real asset to any squad, and he has natural pace and a real eye for a gap. Every time he gets the ball there is huge excitement.
"Most of all, though, it's his desire to improve his own game that makes him such a prospect; he always keeps his standards high, and his hunger to learn from coaches and team-mates is a testament to his professionalism."