Wellington College was his former school.
"I had five years there as a student and 10 years on the staff, with four of these as deputy principal.
"The thought of taking some of the learning and skills which I have grown here at Paraparaumu College and using these to lead Wellington College into the next phase of its long history represented an exciting opportunity for me, which in the end I found too enticing to resist."
Mr Fountain said he would deeply miss the students, staff and families of Paraparaumu College.
He said the Paraparaumu College board would start the process of appointing a new principal soon and "were very confident, with the school in such fine heart, that they will attract a strong field of educational leaders from throughout New Zealand".
A statement from Wellington College said the role of principal at Wellington College was one of the most prestigious appointments in New Zealand education and attracted very high quality candidates from across New Zealand and overseas.
"With the resignation of long-standing and popular headmaster Roger Moses, the board was looking for a combination of educational excellence, proven leadership, connection with boys and boys' education and a modern and future focused vision of Wellington College and how it can best prepare boys for our rapidly changing world.
"The board is confident Mr Fountain has both the personal and professional skills to lead the college into its next exciting era."
"He is an inspiring, inclusive and forward-thinking educational leader."
"Since he became principal at Paraparaumu College, the college has made significant gains in achievement in both NCEA and scholarship pass rates," Wellington College said.
"Its NCEA level two pass rates in 2016 were the best in the college's history."