However, Webster said they made it hard on themselves during the final. "It was 24-0 at half time and [Canterbury] slowly clawed their way back."
He said the boys were elated to get there in the end and the school would look to enter the main division of the tournament next year.
"I think it just goes to show that there is a lot of talent in Rotorua with rugby and rugby league."
The team was co-coached by Ralph Filipo and Thomas Wharerau.
Two Rotorua Boys' High School players - Latu Vaeno and Te Toiroa Tahuriorangi - were named in the tournament team, which included players from both the premiership competition and the developing schools competition.
The premiership competition was won by Auckland's Kelston Boys' High School, who defeated Mt Albert Grammar School in the final.
Rotorua Boys' High School were also awarded the Best Cultural Salute Award on Thursday night for best haka at the tournament.
New Zealand Rugby League football and community general manager Dain Guttenbeil said it was good having the Rotorua school at the tournament.
"New Zealand Rugby League wishes the boys and the school every success in their rugby league journey and we're proud to have been with them for the start of it."
Developing grade final:
Rotorua Boys High School 24 (Bravou 2, Kingi-Murray, Vaeno tries; Tahuriorangi 4 goals) defeated St Thomas of Canterbury College 18 (Van der Velde 2, Falaniko tries; Tatupu 3 goals). H/T: 24-0.