He graduated from the Army Command and Staff College in 1966. He was promoted to the rank of Lieutenant Colonel and became commanding officer of 5RAR from 14 January 1972 to 2 December 1973. His final military postings were Deputy Commander and Commander of 6 Military District in Tasmania in 1974-75.

He resigned his military commission to enter Federal politics and, as the Liberal Party candidate in the June 1975 by-election for Bass in Tasmania, won this previously safe Labor seat. That December he was appointed Minister for Repatriation in the Fraser government and in July 1976 he became Minister for Environment, Housing and Community Development. In December 1978 he was appointed Minister for National Development in the third Fraser Ministry, followed by appointments as Minister for Productivity (December 1979) and Minister of Administrative Services in 1980 (in the 4th Fraser Ministry). He retained this position until the Fraser government was defeated in the 1983 Federal election. He retired from the House of Representatives on 26 October 1984.

Kevin Newman was half of one of Australia's most notable political partnerships having been married since 1961 to the former Senator the Honourable Jocelyn Newman, former Minister for Family and Community Services and Minister Assisting the Prime Minister for the Status of Women. They had two children: Kate and Campbell. Campbell Newman was the Lord Mayor of Brisbane 2004-2011 and is  the current Premier of Queensland (2012 -).

In retirement Kevin Newman was appointed President of the National Trust Tasmania, a member of the Board of the Menzies Foundation and a Director of the Australian Stockman's Hall of Fame in Longreach, Queensland. He was Chairman of the Old Parliament House Governing Council from 1997 to 1999.

Kevin Newman was awarded an Officer of the Order of Australia in the Queen's Birthday Honours of 1994. He died from Lupus Disease in July 1999 and was farewelled with a State funeral.