He was Roger Francis McGill, 61, of Kaukapakapa.
Mr McGill was taking part in a week-long hunt organised by the Northland Hunt Club when the lightning strike occurred just before 1pm on a farm at Mahuta, near Dargaville.
Mr McGill and his mount were killed instantly. Efforts to revive him were unsuccessful.
Other members of the riding group were taken to hospital to be treated for symptoms of mild electrical shock.
Mr McGill was the first of eight people killed in violent storm activity across the top half of the North Island on Tuesday.
Seven others died when swept away in a rain-fuelled rapidly rising riving while undertaking an outdoor adventure activity in Mangatepopo Gorge, near National Park, about 4pm.
The seven comprised six pupils and a school teacher.