Mr Peek arrived at CIT Group in 2003 and oversaw what proved to be a turbulent time in the firm's history.
It lost around $5 billion at the height of the financial crisis, only emerging from bankruptcy protection at the start of this year, after which Mr Peek left the firm, reports Bloomberg.
In his new job at Barclays Capital, he will have an advisory role for clients in the financial services industry.
Hugh McGee, head of investment banking at the division, said: "Our clients will benefit from the unique depth and diversity of his experience."
Mr Peek has also previously worked for Merrill Lynch and Credit Suisse.
Earlier this week, Barclays confirmed that Bob Diamond is to be its new chief executive, replacing outgoing head John Varley in the role from March 31st 2011.
By Gary Cooper