The former Otago Boys' High School pupil won outstanding scholar awards for his results in his 2015 scholarship calculus, statistics and physics exams.
The 18-year-old was the only Otago secondary pupil to win an outstanding scholar award, let alone three.
But he yesterday declined to discuss his achievement.
Mr Mottershead, who will study at the University of Otago this year, was an Otago Daily Times Class Act winner last year for his achievements in mathematics and music.
He completed NCEA level 3 in 2014 - a year before his fellow classmates - and last year he spent his maths lessons studying maths at Canterbury University via correspondence.
The outstanding scholarship award win announced yesterday was not his first.
In 2014, while still in year 12, he gained a scholarship award for calculus and an outstanding scholar award for biology - something usually achieved by New Zealand's top year 13 pupils.
Otago Boys' High School rector Richard Hall was delighted with his former pupil's results.
"Johnny is an excellent scholar and a humble man.
"Last year he was a Class Act recipient and dux of our school. He was top 15 in the country in the Eton Mathematics exam, also attending two Olympiad Mathematics training camps.''
Mr Hall said overall, pupils at the school received 21 scholarships, which equalled the school's record number.
"The 21 scholarships included 18 at scholarship level and 3 at outstanding level across nine different subject areas.
"A lot of work goes into gaining a scholarship, from the teachers, students and parents, so when a boy achieves so highly, we are very pleased.
"Last year we implemented a ‘Gold' group of scholarship students. We have also begun a gifted and talented programme linked to our school's proud history of Rhodes scholars, and we also focused particularly on the skill of academic writing.
"Clearly, it seems to have paid off,'' he said.
Mr Mottershead was among about 8000 pupils who participated in New Zealand Scholarship examinations last year, and 2381 pupils were awarded one or more subject scholarships.
New Zealand Qualifications Authority deputy chief executive Kristine Kilkelly said New Zealand Scholarship was regarded as the most prestigious secondary school award available in New Zealand.
"Students are required to demonstrate a very high level of critical thinking and clear application of knowledge, skills and ideas.
"The students gaining New Zealand Scholarship are the best of the best, and their hard work throughout the school year is reflected in these results.''
Premier award and outstanding scholar award winners were notified of their results online yesterday, and will receive official confirmation from NZQA in the mail.
Scholarship award winners can receive up to $2000 a year, for up to three years, as long as the recipient maintains at least a B grade average pass rating each year of their tertiary study.
Mr Mottershead will use his scholarship funds to study mathematics and music at the University of Otago this year.
