In his parliamentary term in the Commonwealth Parliament Ferguson concentrated on issues such as education, health, family and employment and served on numerous parliamentary and backbench committees. He was the secretary of the Government Education, Science and Training policy committee and is acknowledged as having played a key role in brokering the passage of the Voluntary Student Unionism legislation through the Senate with his (implemented) proposal for a sports infrastructure transition fund. Soon after the 2007 election when he failed to be elected, Ferguson was appointed as the
CEO of the Clifford Craig Medical Research Trust. He was subsequently elected to the
Tasmanian House of Assembly at the
2010 state election, As Health Minister, Ferguson led a somewhat contentious reform of the Tasmanian health system by merging the previously three health services into one and changing the services delivered at each of the four hospitals in the state. He has also took charge of the redevelopment of the Royal Hobart Hospital which led to the long-promised buildings eventuated. One of the highlights of his tenure is the ramping up of health funding and the number of surgeries provided, leading to a historic reduction in the number of people waiting for elective surgery and the introduction of a statewide helicopter network including helipads at each of the state's four major hospitals. His tenure was not been without incident with his appointment of an interim CEO of the merged health service having a side interest in alternative therapies and a series of electrical and computer failures at the ambulance service. In June 2019 Premier Will Hodgman announced a reshuffle arising from Jacquie Petrusma stepping down from Cabinet for health reasons. Sarah Courtney was appointed to the health portfolio. Ferguson was installed as Minister for Infrastructure and Transport, Minister for State Growth and Minister for Small Business. He continued his existing roles as Minister for Science and Technology and Leader of the House. Premier Will Hodgman praised Ferguson for doing an extraordinary job, saying, "He has without doubt been one of the state's greatest health ministers, he has done an outstanding job. In January 2020, Premier Will Hodgman resigned and Ferguson was a candidate to succeed him as Premier and Liberal leader but ultimately withdrew from the leadership contest. Treasurer Peter Gutwein was instead elected unopposed as Hodgman's successor. There was speculation that Ferguson would succeed Gutwein as Treasurer but in the end Premier Gutwein chose to retain the Treasury portfolio, appointing Ferguson as Minister for Finance. On 8 April 2022, after Gutwein resigned as Premier, deputy party leader
Jeremy Rockliff became party leader, and Ferguson was elected as deputy party leader to replace Rockliff. Ferguson was sworn in as
Deputy Premier of Tasmania that afternoon. Ferguson was also sworn in as Treasurer.
Resignation as minister Significant problems with the construction of two new '
Spirit of Tasmania' ferries, including Ukraine-related production delays, cost blow-outs, ongoing arguments with the ferry management board and the port authority, plus bungled tender procurement and design of the berth by the state-owned TT-Line Company to accommodate the new ferries resulted in his resignation as Minister for Infrastructure. He continued to hold the position of Deputy Premier and State Treasurer. Anticipating a successful no confidence motion in the Tasmanian Parliament the following day, Ferguson resigned from the Cabinet on 14 October 2024, but remained Liberal Member for Bass. Ferguson was re-elected at the
2025 election for the sixth consecutive term. ==Political views==