Sinclair will join the bank in October as global head of compliance for wealth and investment management.
She has been with the city regulator for 18 years, during which time she led redress campaigns for the miss-selling of both PPI and interest rate hedging products.
An FCA spokesperson said a replacement would be found in due course, but they could not reveal further information at this time.
The move will see her reunited with Sir Hector Sants who joined the bank last year as part of its efforts to repair its reputation following its fine for its involvement in the Libor-rate rigging scandal.
In addition to the Libor scandal, Barclays faces regulatory probes into a range of matters including one led by the Serious Fraud Office into a deal which saw it raise billions of pounds from Middle Eastern shareholders during the banking crisis.
A Barclays spokesperson confirmed Sinclair’s appointment and said more information would be provided in the next couple of days.
The first UK Libor criminal case was brought to court last month – find out more here.
