The Streatham MP has been appointed shadow Treasury and business spokesperson by leader of the party Vince Cable. He said: “Chuka has agreed to work in the Commons with our business and economy team, alongside Susan Kramer and Chris Fox who speak on these issues in the House of Lords. His experience as shadow business secretary will be invaluable to the party in pursuing our shared values.”
Mr Umunna joined the Lib Dems last Thursday, just 10 days after leaving Change UK, which received three percent of the vote in the recent European elections.
He also quit the Labour Party after nearly 10 years as an MP, partly blaming the antisemitism row and its Brexit stance.
He has been welcomed warmly to the Lib Dems by senior Lib Dem MPs including Jo Swinson, who is the frontrunner to replace Mr Cable when he steps down in July.
Mr Cable is also holding talks with other Change UK MPs, including the former Conservatives Heidi Allen and Sarah Wollaston, the Observer reports, although this has not been confirmed.
The Lib Dems also reported they had received 800 new members just hours after Mr Umunna joined.
The party is currently embroiled in disagreements over how the pro-Remain parties can work together to help overthrow Brexit at the next general election.
There are said to be fears a general election could be only months away if Boris Johnson becomes the next Prime Minister and tries to leave the EU with no deal.
Mr Umunna’s move has also confused some of his constituents in Streatham, as he has not given up his seat.
Erica Martin, 42, said: “I think we as the constituents should have a say on whether he remains our leader.
“At the moment the Conservatives are choosing a new leader to be Prime Minister and it’s the same thing- we don’t have a say as voters.
“There’s no clear standard of policy for anyone to follow. Where does he stand? It’s like he doesn’t know his own mind.”
But Antiques shop owner Steve Wright, 67, doesn’t think Mr Umunna should face a by-election as he thinks a general election could be soon.
He said: “I think they should just leave him alone.
“He’s doing a good job in Streatham anyway, so why should we rock the boat and elect somebody else?
“I would probably vote for him because he is a man of principle.
“I think people should vote for candidates based on who they are and what they do, rather than which political party they follow the whip for.”