At the council meeting yesterday it agreed the chief executive's proposals to restructure the top tier.
Mr Jones and Ms Smith have decided to pursue other interests, but both expressed good wishes for the council and its future.
Ms Smith said: 'I have a high regard both for councillors and my colleagues at East Staffordshire, who are committed, hard working and professional and I have made some good friends, both inside and outside the council. I will always think of the council with affection and have thoroughly enjoyed my time working here, but this is an opportunity to branch out into other areas.'
Mr Jones said: 'I have devoted over 20 years of my life to working for the council and have been rewarded with a series of interesting jobs and wonderful support from officers and councillors. I wish the council every success in the future in its drive to improve the lives of the people of East Staffordshire.'
Council leader Alex Fox said: 'Marie Ainsworth's proposals for the structure show that the council is determined to continue to modernise and to concentrate on issues important to local people. Keith and Lynne have both given excellent service to the council and its tax payers. We can understand the opportunities they wish to take and we wish them all the very best for the future.'
Leader of the opposition, Julian Mott, said: 'Both Lynne and Keith have been excellent officers for the council for many years. I've worked closely with both of them and they've been very professional and managed their services well. They'll be a hard act to follow and I wish them well for the future.'
Mr Jones will leave the council on 31 May and Ms Smith will leave on 31 July. An appointment for the position of director of corporate affairs will be announced in due course.