She was a former vice-chairman at the firm founded by her late father John Murphy.
Her departure is believed to have followed a disagreement with the current board over handing ownership of the company to its employees.
Caroline Murphy said: “Following eight years with the Murphy Group, I have formally decided to exit the company.
“My father John Murphy, remains a great inspiration to me. I was delighted to have seen the company grow in strength during the years I worked to embed his values into the structure of the Murphy Group.
“The natural extension of my father’s values in my view, is the development of the Murphy Group into an Employee Owned structure.
“I believe the future of his legacy is best entrusted into the capable hands of its people.
“I have been vocal in my belief that leadership of this business must include those working on the ground if it is to continue to deliver for the clients who have placed their trust in us over the years.
“Taking into account the direction of the board’s interests, the current structure holds no space for me to develop this process further.
“I wish all within the Murphy Group the greatest success for the future. I hope the company goes on to represent my father and continues to provide work and opportunity for many years to come.”
Caroline said she would continue to work for company shares held in her name to be transferred into an employee-owned structure.
Her shares are held in a trust scheduled for the benefit of the Murphy family consisting of John Murphy’s four children and his wife.