Nicolson served as the SNP Member of Parliament (MP) for Ochil and South Perthshire from 2019 general election until the seat's abolition in 2024.

[12] After graduating from Harvard, he worked as a speechwriter on Capitol Hill for Senator Daniel Patrick Moynihan specialising in Israel-Palestinian issues, the Irish peace process, and gun control.

[13] He moved back to the UK from Washington, D.C. to work full-time for the BBC when offered a job presenting the network 'DEF 2' youth strand discussion programme Open to Question.

[15] The documentary examined the discriminatory laws targeting gay men in the UK, and asked why the Conservative Party continued to support them.

He went on to work as a reporter for a range of high-profile BBC news and current affairs shows including Panorama,[14] Assignment, and Newsnight.

Of the broadcast, Nicolson said, "My time on air seemed dream like, with hours passing in an instant, and yet individual moments seeming to linger endlessly.

In stark contrast to the BBC, his ITV bosses were happy to go over time if the party's press office was unhappy with his probing questions to a politician.

He is a regular commentator on UK politics for American audiences on the Cumulus Media Networks radio programme The John Batchelor Show.

[32] John Nicolson joined the Scottish National Party aged 16,[33] but let his membership lapse whilst working as a BBC and ITV journalist.

[37][38] He also campaigned for the establishment of a separate BBC Scottish Six O'Clock News – a proposal which won the unanimous support of members of the Commons Culture, Media and Sport Select Committee on which he sat.

[40] Nicolson used his position to cross examine the BBC Chair Rona Fairhead, revealing the unorthodox way in which she had been appointed without due process.

[44] He was also actively involved in the parliamentary inquiries into "fake news",[45] the abuse of ticket sales by touts,[46] complaints against the press,[47] combating doping in sport,[48] and the impact of Brexit on the creative industries, tourism and the digital single market.

[51][52] In 2016, Nicolson put forward a Private Member's Bill for an 'Alan Turing law' which would retrospectively pardon all gay men who had been convicted of offences no longer on the statute books.

[56] In 2016, The Herald newspaper dubbed him "bottom of the league for written questions", after reporting that he had submitted fewer than any other newly elected SNP MP.

"[57] In 2016, Nicolson repeatedly criticised on social media STV's Digital Politics and Comment Editor, Stephen Daisley, who had published critical opinion pieces about the SNP.

[67] During the 2019 general election campaign, Nicolson was heckled at a hustings in Alloa after telling the audience, "Only the Scottish National Party can beat the Tories here in East Dunbartonshire.

[72][73][74] As a member of the CMS Committee,[75] Nicolson has taken evidence from witnesses and cross-examined ministers as part of inquiries on a number of issues including public service broadcasting,[76] the economics of music streaming,[77] concussion in sport[78] and the impact of Brexit and the COVID-19 pandemic on culture and the arts.

[79][80][81] During the first coronavirus lockdown, Nicolson fundraised to donate tablet devices to hospitals serving constituents of Ochil and South Perthshire, so that patients in COVID-19 ICU wards could stay in contact with friends and family members.

[85] In March 2021, Nicolson called for a debate in parliament on the disposal of unexploded mines and bombs on the seabed left there during the World Wars: "These explosions will kill any sea life nearby.