The decision to end the £20 a week temporary uplift – introduced as a temporary measure during the coronavirus crisis – will cost each of them about £1,000 a year.
Department for Work and Pensions figures show there were 24,288 people claiming the benefit in the area in July – the latest available data and, of those, 58% were not in work.
They are among more than 5.8 million claimants across the UK who may face a struggle to make ends meet, according to anti-poverty campaigners.
Despite months of campaigning, the uplift ended on October 6, with claimants expected to receive final payments containing the uplift by October 13.
Katie Schmuecker, from anti-povery group the the Joseph Rowntree Foundation, said: "The Prime Minister is abandoning millions to hunger and hardship with his eyes wide open.
"This decision flies in the face of the Government' s mission to unite and level up our country".
A Government spokesperson said: “We’ve always been clear that the uplift to Universal Credit and the furlough scheme were temporary.
"They were designed to help claimants through the economic shock and financial disruption of the toughest stages of the pandemic, and they have done so."
He said Universal Credit would continue to provide support for people but added that it was right for the Government to now focus on its Plan for Jobs, which aims to support people back into work and help those already working to progress.