Blackford became the SNP Westminster leader after Angus Robertson lost his seat at the 2017 snap general election.

[6] Following 20 years in the financial industry, he left to do independent consultancy work, forming an investor relations company called First Seer in 2002.

[11] In 2013, he helped explain the business case for not closing a primary school in Milngavie when East Dunbartonshire Council had proposed closure.

[14] He was previously the chairman of the Glendale Trust, an organisation responsible for a community-owned estate on Skye, which made an approach to Highland Council to bring a historic pier under community control.

[17][18] Blackford stood as the SNP candidate for the Ayr constituency at the 1997 general election, but finished in third place behind Sandra Osborne of the Labour Party.

Blackford had been treasurer of the SNP and during this time he began to be viewed as a critic of the party leader, Alex Salmond.

[23] Blackford's reputedly hard line over financial matters had led to a breakdown of trust between him and the national executive and at one point he even threatened to sue party leader, Alex Salmond, for defamation.

"[25] Blackford has argued for better telecommunication infrastructure for rural areas, noting that video-conferencing is one way of overcoming travel time and in the absence of air links.

[29] Following the electorate's decision to reject independence at the referendum on 18 September 2014, Blackford argued that Scotland should consider the constitutional change offered by the main unionist parties.

[32] The campaign attracted national attention because of its acrimony; Blackford objected to being called a "well-funded banker" and confronted incumbent MP Charles Kennedy in his office.

[36] Former Liberal Democrat leader Menzies Campbell labelled the campaign, "far and away the most despicable I encountered in all my years in UK politics.

On 14 June 2017, he was elected as leader of the SNP Westminster Group, succeeding Angus Robertson who had lost his seat.

In June 2022, Grady apologised for the behaviour in parliament after a full independent investigation and was suspended from the House of Commons for two-days[47] over his unwanted sexual advance to a junior SNP colleague in 2016.

"[56] Blackford's contributions in the Commons were often greeted with theatrical groans from Conservative MPs—many of whom left as soon as he got to his feet[57][58]—and one journalist, Esther Webber, remarked that his questions gave people a "chance to catch up on life admin.

Blackford had raised a question to Prime Minister Theresa May regarding the issues of no Scottish MP being given time to debate the Scotland-related areas of the EU Withdrawal Bill the previous night and also wanting the chamber to immediately have a vote on the motion to sit in private.

[68] He previously earned an additional £1,000 a month serving as chairman of Commsworld - a telecoms business in which he owned circa £70,000 worth of shares.

[73] Blackford is a member of the Free Church of Scotland, but has had some disagreements with them by voting for abortion rights and same-sex marriage.