“I am looking forward to working to get a better deal for the residents of Borehamwood.
“I am particularly grateful to my local constituency and branch Labour parties whose dedication and commitment enabled me to contest this seat whilst observing Succot without compromise."
In June’s general election, Mr Newmark narrowly failed to win the Finchley and Golders Green constituency for Labour from Mike Freer, the Conservative MP.
Mr Corbyn’s official Twitter feed described the victory in Borehamwood on Thursday as a “fantastic result for Labour and Hertfordshire”.
In a close run vote, Mr Newmark won 383 votes.
The turn-out for the election was 21.84 per cent.