Michael O'Sullivan has resigned from his role as president and COO at US off-price apparel and home fashion retailer Ross Stores.

In a statement, Ross Stores said O'Sullivan, who has served in the post since 2009, has resigned from the company and its board with immediate effect.

"Michael has made numerous valuable contributions to the growth and success of our business since he joined Ross in 2003. We thank him and wish him well in his future endeavours," says CEO Barbara Rentler.

"Looking ahead, we are confident in our deep bench of highly talented senior executives. We believe that their proven leadership skills will continue to drive the successful execution of our off-price strategies and thus, maximise our ability to deliver ongoing increases in shareholder value."

Rentler added the retailer expects to make management changes that will be announced over the coming months.

In the interim, Michael Hartshorn, the company's group executive vice president, finance and legal and CFO, and Mike Kobayashi, group executive vice president, supply chain, merchant operations and technology will report directly to Rentler.

In addition, Gary Cribb, group executive vice president, stores and loss prevention, will report to Jim Fassio, president and chief development officer.