 He was the son of Símun Mikkjal Zachariasen from Kirkja and Malena Frederikka Simonsen from Hattarvík, and was the brother of Louis Zachariasen.Símun Petur Zachariasen married Maria Henriksen from Klaksvík, and they were the parents of the politician Álvur Zachariasen.Zachariasen graduated from the Faroese Teachers School in 1908 and worked as a teacher in Klaksvík from 1914 to 1953, and as the editor of the newspaper "Norðlýsið" from 1915 onward.