Chief nursing officer Sarah Mullally is to step down from her post to become a full-time Church of England curate, NHS chief executive Sir Nigel Crisp has announced.

Ms Mullally, who has been at the Department of Health for nearly five years, will become curate of the parish of Battersea Fields, in the diocese of Southwark, south London.

The move ends a career in nursing and management that has taken her from early roles as staff nurse and clinical teacher at St Thomas' Hospital, and specialist cancer nurse at the Royal Marsden to become director of nursing and quality, then acting chief executive at the Chelsea and Westminster Healthcare Trust, before joining the Department of Health in 1999.

Ms Mullally said the decision was "a personal career move". She was ordained as a deacon in the Church of England three years ago and as a priest in 2002, and is currently honorary curate at the Battersea Fields benefice, which covers the churches of St George's and St Saviour's.

Sir Nigel said: "Sarah will be sadly missed. She has made a huge contribution both during her time in the department and her early career in the NHS. As chief nursing officer she has led the development of nursing over the last five years at a time when nurses have taken on new roles and responsibilities."

Health secretary John Reid said: "Under Sarah's leadership, the nursing profession has grown in size, diversity and confidence. There are now 55,000 more nurses than in 1999, and their role has widened considerably.

"In addition to developing new roles in healthcare teams, and taking on new powers to prescribe drugs previously restricted to doctors, there are now more than 3,000 modern matrons, and over 870 nurse consultants. All these changes have made a major difference to the responsiveness of the service and the degree of choice offered to patients."

Ms Mullally said: "I have been very privileged over the last five years to have worked closely with the departmental board, front-line nurses, midwives, allied health professionals and leaders in the voluntary sector. Over that time nurses and midwives have seized many opportunities to improve patient care, and I am proud to have played a part in introducing the changes that have put nurses and midwives at the forefront of better healthcare."

Beverly Malone, general secretary of the Royal College of Nursing, said: "We are sorry that Sarah Mullally has chosen to stand down, but respect her decision and reasons. We will miss her support and wish her well in her new vocation.

"During her time as chief nursing officer she has made a great contribution to improving patient care and championing nurse leadership. She has built a firm foundation for nurses and nursing at a time of significant change."

Sir Nigel said the post would be advertised shortly.