He was born at Halsted Priory on the island of Lolland, Denmark. He was the son of Knud Axelsen Urne til Årsmarke (1564–1622) and Margrethe Eilersdatter Grubbe til Alslev (1568–1654). He was a brother-in-law of Ove Gjedde who married his sister Dorothy Knudsdatter Urne (1600-1667). He attended Sorø Academy 1605-09 and studied 6 years in Europe with his brothers.
He became secretary of the chancellor until he became a treasurer in 1617, which he remained until 1627. In 1627 was granted supervision of Nykøbing and Ålholm and made commissioner-general of the market towns of Lolland and Falster. He served as Steward of Norway from 1629 to 1642. After 13 years in Norway he returned to Denmark, and to the position of national chancellor (rikskansler) from 1646 to 1660. From 1658 he was granted Lyse Abbey which he exchanged the year after for Halsted Priory which he retained until his death in 1663. 
On 18 July 1624 he married Sophie Hansdatter Lindenov (1608-1652), daughter of Hans Johansen Lindenov and Lisbeth Sophie Rantzau. In 1628 they became the parents of Christian Urne (1628–1669) later a magistrate on Funen.