[11] Blackman stood in Bedford at the 1997 general election, coming second with 33.7% of the vote behind the Labour candidate Patrick Hall.

[23] According to the Harrow Times, he was accused of hypocrisy by a former fellow Brent council colleague who claimed she had an 11-year affair with him whilst he was married.

He has been part of several delegations to Israel,[26] including during the Operation Defensive Shield conflict when he visited for an Israeli military briefing on the Iron Dome defence system.

[27] In 2015, the compliance officer for the Independent Parliamentary Standards Authority (IPSA) made a judgement that Blackman had submitted 732 inaccurate mileage claims.

[30][31] On 1 July 2015, Blackman was elected chair of the All Party Political Group on Smoking and Health, after serving as its secretary for several years.

[39][40] In October 2017, Blackman drew criticism from Tom Peck of The Independent for hosting Tapan Ghosh, an anti-Islam extremist from India, at a House of Commons event.

[48][49] Following an interim report on the connections between colonialism and properties now in the care of the National Trust, including links with historic slavery, Blackman was among the signatories of a letter to The Telegraph in November 2020 from the "Common Sense Group" of Conservative Parliamentarians.

[50] Blackman attended a Diwali event held in October 2022 at the Houses of Parliament as a guest of the Hindu Forum of Britain.

Nithya Atmadayananda, a prominent supporter of Nithyananda, was photographed with Blackman and the President of the Hindu Forum of Britain, Trupti Patel.

[59] OpenDemocracy reported in February 2022 that Blackman tabled four pro-regime motions in the House and had written to two foreign secretaries, urging them to strengthen ties with Azerbaijan and condemn its opponent Armenia.

[60] Blackman told the Eye To Eye podcast in July 2020[61] that he "put down positions on behalf of good friends in Azerbaijan" on a regular basis, that [referring to July 2020 Armenian–Azerbaijani clashes] "in these types of conflicts ... whoever gets the best propaganda tends to grab the attention of the listeners and the viewers", adding that in this regard he has been "fed the information through the Azerbaijan embassy in the UK", praising the latter for being "very very helpful and proactive".

[59] Blackman urged the then foreign secretary, Dominic Raab, to take Azerbaijan's side in the 2020 Nagorno-Karabakh war.

[60] On Blackman's Azerbaijan lobbying, Steve Goodrich from anti-corruption group Transparency International UK commented "It's pretty shocking if you've got MPs essentially being briefed by foreign embassies and then making contributions in the House based on what they've been advised to say.

[63] Blackman was appointed Commander of the Order of the British Empire (CBE) in the 2023 Birthday Honours for political and public service.