Woollaston joined the New Zealand Labour Party in 1975. He was Secretary of the Labour Party Policy Council from 1982 to 1984. He was a Golden Bay County Councillor and on the Nelson Regional Airport Authority from 1977 to 1980. Woollaston was also on the Nelson Bays United Council and No 11 District Roads Board from 1979 to 1980. Woollaston stood for the
Nelson electorate in 1981, defeating incumbent MP
Mel Courtney. In 1983 he was appointed as Labour's spokesperson for Local Government by Labour leader
David Lange. During his time in Parliament he was Associate Minister for the Environment (1987–89), Associate Minister of Justice (1987–90), Minister assisting the Deputy Prime Minister (1988–90), Minister of Conservation (1989–90), and
Minister of Local Government (1990). Woollaston was a junior Minister in the controversial Fourth Labour Governments of David Lange & Geoffrey Palmer but never sought at the time (through resignation or public opposition) to distance himself from the
Rogernomics policies of that era. As Associate Minister for the Environment Philip Woollaston helped broker the Montreal Protocol, working through the night in Montreal, Canada, to successfully draw together parties before the looming deadline, when Europe was largely hedging around the deal. The Montreal Protocol was the first global treaty to bring together a majority of nations over global environmental concerns, in this case being the use of
chlorofluorocarbons (CFCs) as refrigerants and discovering that they were destroying the stratospheric ozone layer which prevents harmful ultraviolet light from entering the lower atmosphere. In 1990 Woollaston retired from Parliament and was replaced as MP for Nelson by
John Blincoe. On 6 December 1990, he was granted the title "The Honourable" for life, in recognition of his services as a member of the Executive Council. In 1991 he became Policy Advisor to the executive director of the
United Nations Environment Programme in Nairobi, Kenya for two years. == Mayor ==