At the 440-pupil Welsh-medium primary in Caerphilly county borough, more than 200 children attend at least one extra-curricular club, said Mr Griffiths.
"We're talking about chess, literacy, modern foreign languages, sporting clubs, dance clubs.
"If they regularly attend those clubs they can end up representing the school which leads to a feeling of self-worth and self-esteem," he said.
"Children don't want to miss out and quite often our parents say 'they're not feeling 100% but they want to be in school because they enjoy being in school'."
The school scrapped certificates for 100% attendance following feedback from parents, though overall data for every class is put on the school's website weekly.
Absence for holidays is not approved in the first half term of the school year but there is a flexible approach after that.
Mr Griffiths, who shares the headship at Ysgol Gymraeg Caerffili with colleague Eleri Jones, said there was not "one specific" reason for high attendance but key factors include "high-quality teaching" and good relationships between staff, parents and pupils.
"For some families we have to have far more dialogue than others and it's recognising those families with specific needs and working closely with them to ensure that their children can feel comfortable in school," Mr Griffiths said.