[2] Parkinson was born in North Shields, and attended Park House School in Newbury, Berkshire, before reading History at Emmanuel College, Cambridge, from 2001 to 2004, where he graduated with a BA (proceeding MA).

[9] In October 2015, Parkinson left his role as Special Adviser at the Home Office to become National Organiser of the ground operation for the successful Vote Leave campaign in the 2016 United Kingdom European Union membership referendum.

Parkinson had declared his interest in standing for a winnable constituency at the 2015 general election, and had been tipped for the shortlist in safe seats such as Richmond, Yorkshire; but in December 2014, he and another of May's Special Advisers, Nick Timothy, became involved in a candidate selection row.

Both were removed from the Conservative Party's list of approved candidates by Party Chairman Grant Shapps, reportedly on the instructions of David Cameron, because of his growing alarm at having such key allies of a leadership rival such as Theresa May in the House of Commons, and Parkinson and Timothy were given the pretext that neither had campaigned in the Rochester and Strood by-election (with such campaigning being a requirement of candidates staying on the approved list).

[9][13][14] On 28 April 2017, with Prime Minister Theresa May having called a snap general election ten days earlier, it was reported that Parkinson had been shortlisted for the "safe seat" of Saffron Walden, following veteran MP Sir Alan (now Lord) Haselhurst announcing his retirement from the Commons.

[15] Analysing the shortlist, former MP and ConservativeHome Executive Editor Paul Goodman noted that, "Nor to date have SpAds been shoehorned into constituencies against weak opposition", but that, "The case of Saffron Walden is perhaps more suggestive.

Stephen Parkinson, the Prime Minister's Political Secretary and the former head of the ground campaign at Vote Leave, is up against Katherine Bennett, who hasn't fought a Parliamentary election previously, and Kemi Badenoch, a member of the London Assembly who was beaten in the first round in [the Conservative selection contest for] Hampstead and Kilburn.

He was nominated for a life peerage in Theresa May's resignation honours, being created Baron Parkinson of Whitley Bay, of Beyton in the County of Suffolk on 8 October 2019.

[31] Sanni said in subsequent media appearances that he had to organise security for his family who live in Pakistan because of the unlawful status of homosexuality within the country, and accused Parkinson of "outing him" against his will.