Kier has announced that group finance director Deena Mattar is to leave the construction company, with effect from November 2010.
She will be replaced by Balfour Beatty's deputy finance director Haydn Mursell.
A statement from Kier said she was leaving “to pursue other opportunities”.
The 44-year-old Mattar, who joined the group in 1998 and became group finance director in 2001, found herself in the media spotlight four years ago when it emerged she was having an affair with Kier's group chief executive John Dodds, 20 years her senior.
Dodds would eventually leave his wife and marry Mattar. He retired from Kier in March.
Mursell will join Kier as group finance director designate on 18 August 2010 and will take over from Mattar when she departs following the firm's November AGM.
He has been deputy group finance director of Balfour Beatty since October 2008, and was previously chief financial officer at Bovis Lend Lease.