She told the board her decision to leave was so she could pursue other interests.
Sergeant will leave the at the end of January 2011 and Lloyds group is now searching for a replacement.
Sergeant was the first chief risk officer to be appointed to the Group Executive Committee of Lloyds TSB in March 2004.
Since this time Lloyds says she has developed and embedded a robust risk discipline in Lloyds TSB and spearheaded its implementation in the enlarged Lloyds Banking Group.
Alongside her risk management responsibilities, Sergeant has also played a key role in developing and delivering its public affairs programme.
Eric Daniels, group chief executive at Lloyds group, says: “I am very grateful to Carol for the contribution she has made to the group as a key member of its Executive Committee. She has established an outstanding Risk leadership team and has implemented industry-leading risk management standards and practices. We wish her every success for the future.”
Sergeant says: “I am very proud of what we at Lloyds Banking Group have achieved together during a period of enormous change for the financial services industry. The group is on a good trajectory, underpinned by a strong Risk function and risk management disciplines, and I believe now is the right time for me to seek new challenges.”