He was the son of Nicholas I Szécsi, the Palatine of Hungary (1385–1386) and Margit Debreceni, granddaughter of former palatine Dózsa Debreceni.
He had three brothers, including Frank, who served as Royal treasurer between 1394 and 1396.
Nicholas II married Helen Garay, daughter of Nicholas I Garay, they had eight children, including Cardinal Dénes Szécsi, Archbishop of Esztergom.
Nicholas served as Royal treasurer from May to December 1397.
He functioned as secular gubernator of the Roman Catholic Diocese of Veszprém between 1403 and 1405.