Megan Butler will be joining the FCA on secondment from the Prudential Regulation Authority, while current director Christopher Woolard has been added to the board.
Ms Butler will take up the role of director of supervision - investment, wholesale and specialists.
She will take over from Tracey McDermott who will become acting chief executive of the FCA on the 12 September following the departure of Mr Wheatley.
It was announced earlier this month that Martin Wheatley will stand down as chief executive, with Chancellor George Osborne saying that a change of leadership was needed.
Ms Butler currently holds the position of executive director of international banks directorate at the PRA and will take up her new role on 1 September for a year.
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Ms Butler’s previous roles included head of the department responsible for the supervision of the UK operations of the major investment banks for the Bank of England as well as head of enforcement law and policy at the FSA.
Prior to this she chaired the International Organisation of Securities Commissions Standing Committee on cross border cooperation and enforcement from 2004-2008.
Mr Wheatley said: "I am delighted that Megan has decided to join the FCA. She brings with her a wealth of experience and an excellent reputation in wholesale markets and will be a valuable addition to the executive team."
The Treasury has appointed director of strategy and competition Mr Woolard, a former group director and content board member at Ofcom, to the FCA board for a three year term starting 1 August 2015.
He has spent most of his career in regulation or policy development including working at the BBC and as a senior civil servant at the Department of Trade and Industry.
FCA Chairman John Griffith-Jones said: "Christopher has been a vital member of the FCA’s Executive Committee since the inception of the organisation, in particular shaping the strategy launched in December last year and our approach to competition.
“He will bring invaluable experience and judgement to the board from his time at the FCA, but also outside the financial sector.”
Mr Woolard said: "I am joining the board at an important juncture for the FCA. I look forward to helping the board ensure that the FCA is able to meet the many challenges ahead of it.”
He joined the FCA in January 2013 as director of policy, risk and research which became strategy and competition in December 2014. He is a non-executive member of the board of the Payment Systems Regulator and is a Sloan Fellow of London Business School.