Liam Conlon beat Medical Aid for Palestinians CEO Melanie Ward in a fiercely close selection battle for the Beckenham and Penge constituency on Wednesday night.
The new seat in Bromley was created after the Boundary Commission review. The area is currently held by retiring MP Bob Stewart, who surrendered the Tory whip earlier this month when he was convicted of a racially aggravated public order offence.
The constituency is tipped to fall to Labour at the next General Election.
Mr Conlon stresses a focus on the NHS and disability rights after a “life-changing accident” when he was 13 left him unable to walk for four years.
"Beckenham and Penge is home to some of the most beautiful green spaces in London, thriving local businesses, and an unrivalled community spirit," he said in a statement on Thursday.
"But I know too many hardworking families are struggling with the cost of living, record NHS waiting lists, and soaring rents and mortgages. I want to change that, and be an active, visible local MP - and give our new constituency the representation it needs and deserves."
On his website Mr Conlon lists himself as the vice chair of the Lewisham West and Penge Constituency Labour Party, national chair of the Labour Party Irish Society and a disabilities officer at the Communication Workers Union (CWU).
Earlier this year Sir Keir Starmer appointed the former senior civil servant his chief of staff – which prompted conflict-of-interest accusations from Boris Johnson's supporters.
The anti-sleaze watchdog, the Advisory Committee on Business Appointments, recommended a six-month delay between her leaving the civil service and starting the job in the Labour leader’s office.