The on-loan Hoops winger expressed his delight at seeing his fellow youngster net his first for the club.
In their last match under Ronny Deila, the Hoops signed off in emphatic style with a 7-0 win over Motherwell at Parkhead, with Tierney opening the scoring after 21 minutes.
It was a fitting way for the 18-year-old to sign off his tremendous campaign, which has seen him establish himself as the club's first choice on the left side of defence and make 32 appearances in all competitions, as well as make his debut for the Scotland senior side.
Roberts, who himself is enjoying a successful breakthrough at the Bhoys since his January loan move from Manchester City, was quick to lavish praise on Tierney after the match.
The winger tweeted: "Great way to end the season. Thrilled for Kieran Tierney to cap off an amazing season with his first goal. #5inarow."
Roberts and Tierney have been two of the brightest stars for Celtic this season, and whilst Roberts will be at the club next season after signing an 18-month loan deal at the start of the year, the Bhoys may have to work hard to fend off interest in Tierney.
Back in February, Spanish outlet Marca named the youngster as the best teenage left-back in Europe, and his reputation already seems to be spreading to continental Europe after such a stellar debut campaign.