Walsh was elected to the Legislative Assembly at the
2002 election, easily retaining the seat for the National Party after the retirement of long-serving MP
Barry Steggall. He was re-elected at the 2006 and 2010 elections, receiving 79.3% of the two-party preferred vote in 2010. In 2014, defamation proceedings were commenced against Walsh by Environment East Gippsland. Walsh entered into a confidential settlement with the environmental group, the terms of which required him to post a public apology on his official website. In the wake of the Coalition losing government at the 2014 election, outgoing Deputy Premier Peter Ryan retired from the party leadership, declaring that it was time for generational change. Walsh emerged as the sole candidate for the leadership to succeed Ryan, and was
elected unopposed. Under Walsh and Ryan the National Party has taken a more centrist stance. The newly-elected Labor Government pursued Walsh over alleged mismanagement and interference with the Office of Living Victoria (OLV) during the four years that Walsh was
Water Minister, following findings by the State Ombudsman released prior to the 2014 election that Walsh had repeatedly meddled with staffing decisions, operational management, overseen breaches of government procurement rules, and multiple undeclared conflicts of interest that saw several lucrative government contracts awarded to former National Party consultants and advisers without going to public tender. Abolishing the OLV was one of Premier
Daniel Andrews' first actions upon taking office, followed by the appointment of former auditor-general Des Pearson to investigate the OLV. Pearson identified rampant management failures typified by a lack of measurable objectives, lack of proper records and due diligence or record-keeping, over 90% of funded projects failing to achieve completion by deadline, $3.6 million in taxpayer funds having gone missing, and the funding of a smartphone app which never materialised. Labor Water Minister
Lisa Neville subsequently announced that she was seeking to recover a number of questionable grants made during Walsh's tenure as minister, including a $500,000 grant to colourful property spruiker Henry Kaye for the construction of an "architectural masterpiece" in Melbourne's western suburbs that never eventuated and instead remains a disused rubbish dump. The 2018 election was a landslide victory for the
Australian Labor Party under
Daniel Andrews that saw the Nationals reduced to 7 seats, the lowest representation in the party's history. The party was reduced to just 1 seat in the upper house after
Luke O'Sullivan lost in the Northern Victoria Region, whilst
Peter Crisp lost
Mildura to an independent and the party placed third and fourth place in place in its formerly safe seats of Shepparton and Morwell, respectively. Walsh was re-elected unopposed as leader alongside
Steph Ryan as deputy leader and pledged to work harder to represent regional Victoria. Following Barnaby Joyce's return to the deputy prime ministership in February 2021, Walsh emerged as a factional player in federal politics by attempting to disaffiliate the Victorian Nationals from the Federal Nationals over dissatisfaction with Joyce's opposition to a net zero carbon emissions policy. However, the Victorian Nationals management board rejected Walsh's disaffiliation motion, and the party's state council passed a contrary motion to congratulate Joyce on his return to the federal leadership. In February 2022, Walsh, along with
Matthew Guy,
David Davis,
Gary Blackwood and
Melina Bath, were fined $100 each for breaching face mask rules, after the Coalition MPs were photographed maskless while attending an event in Parliament House. The controversy surrounding former Morwell MP
Russell Northe's gambling debts dogged Walsh's leadership during this term, who declined to comment on Northe's conviction and imprisonment, despite Walsh having loaned significant sums to finance Northe's gambling addition. On Monday 25 November 2024, Walsh resigned as leader of the Nationals and was replaced as party leader by Gippsland South MP
Danny O'Brien at a late night partyroom meeting. Media were informed of the change the following day, with Walsh moving to the backbench for the remainder of the parliamentary term and earning praise from Labor Treasurer Tim Pallas. ==Personal life==