Borell said he enjoyed the many leadership challenges the programme presented and wanted to encourage other young Māori to apply.
"The Tuia programme is not just a year-long programme, it's lifelong," he said.
Working closely with Webber was a "cool' and insightful experience, Borell said.
"It was a really great as Garry is a strong supporter of the Maori wards and also really understands the struggles that young people face to get their voices heard. It's really encouraging to know I have his support, " he said.
Borell has an impressive CV - he gained seven scholarships while at Tauranga Boys' College and is the youngest member of the Pirirākau hapū's Management Committee.
In 2017 he completed his first year in Pharmacy studies at Auckland University but struggled after the death of his beloved mother Paula Heke in a car crash in 2016.
He was 17 and his 19-year-old sister Alana, who lives in London, was 16 at the time.
"My mother's death hit me really hard and it was the catalyst for the demise of my mental health and wellbeing last year. I really struggled so I took a gap year," he said.
"As a young Maori man, in fact, like lots of men, we don't like to ask for help but I am so thankful for all the love and support I have received from my whanau and friends. "
Next month Borrel starts his Bachelor of Law and Commerce degree at Auckland University, something he said he was keenly looking forward to.
When asked who had inspired his political aspirations Borell said it was not one particular person but he had drawn inspiration from the best traits of many leaders he looked up to.
"Outside my whanau, I really look up to Dr Lance O'Sullivan who is a fantastic leader role model and I also admire Marcus Akuhata-Brown, who is a gifted teacher and strong advocate for youth particularly those at-risk."
O'Sullivan is a Northland GP, medical innovator and former New Zealander of the Year.
Borell said he began the Tuia programme with an eye to a future career in government as he wanted to make a "real difference" locally and nationally, and possibly internationally.
"I want to become an instrument for making positive changes and hopefully inspire other young people to get more involved in doing good in their community."
Mayor Webber and Council's Maori relationships advisor Chris Nepia attended Cale's Tuia Te Here Tangata graduation at Bastion Point, Auckland, in December last year.
"When Cale joined the programme he was a little uncertain as to the path he should travel. But with the learnings from the programme, and support from whanau, friends and the community, coupled with his own self-belief and determination, I am sure he will continue to grow as a leader," Webber said.