He joins Number 10 from the Hakluyt, a strategic advisory firm for businesses and investors, where he has worked since 2016. Previously he was a director at Bank of America.
Mr Rosenfield will start on December 7, but Lord Udny-Lister will continue to serve as acting chief of staff until January 1.
In Manchester he grew up as a member of the Sha'are Shalom Reform shul.
He also became involved with the RSY-Netzer youth movement. In 2012 he was involved with the financial side of the London Olympics.
Former Downing Street director of communications Lee Cain, a key all of Dominic Cummings, was said to have been offered the post earlier this month.
But a row saw Mr Cummings and Mr Cain both depart from their jobs.
As a member of the Jewish Leadership Council, Mr Rosenfield was amongst the delegation of communal leaders to meet ex-PM Theresa May at Downing Street in 2017.
Addressing the WJR annual dinner in February, Mr Rosenfield told the audience: “Look out beyond our own families and communities to those in the wider Jewish world less fortunate than us. Look out beyond our own to those struggling in the face of disaster.”
He took over as WJR chair in 2016.
