LONDON — Sir Andrew Witty, chief executive officer of GlaxoSmithKline plc, plans to retire from the company next year.

GSK announced Witty’s retirement Thursday in releasing its 2015 annual report to shareholders. Plans call for Witty to step down from the CEO post on March 31, 2017.

Andrew Witty

The board of directors plans to conduct a search for a successor and will consider internal and external candidates for the role, according to GSK.

“GSK is a very special company, with an inspiring mission and many dedicated people. By next year, I will have been CEO for nearly 10 years, and I believe this will be the right time for a new leader to take over,” Witty said in a statement.

“In making this decision, it has been important to me that the board have the time to conduct a full and proper process and that we sustain the momentum of our current business performance, capitalizing on the very significant progress we made last year to strengthen the group,” he explained. “By doing so we will strongly position GSK to achieve the medium-term outlook set out to investors last year and deliver a return to core earnings growth in 2016.”

Witty, also a board member, has served as CEO of GSK since May 2008. He joined GSK in 1985 and has held various sales and marketing roles in the United Kingdom and abroad, including working in the International New Products groups, both in the respiratory and HIV/infectious disease fields. Witty also has worked in South Africa, the United States and Singapore, where he led the group’s operations as senior vice president for Asia Pacific. In 2003, he was appointed president of GSK Europe and joined the company’s corporate executive team.

GSK said Witty also has served in advisory roles to governments worldwide, including South Africa, Singapore, Guangzhou China and the United Kingdom, where he was a member of the prime minister’s Business Advisory Group from 2010 to 2015.  He was awarded a knighthood for services to the economy and to the U.K. pharmaceutical industry in the 2012 New Year Honours List.

In 2014, Witty was named as a business ambassador for the U.K. government, and last year he became a member of the China-Britain Business Council Advisory Council.

“Andrew’s retirement next year will represent the culmination of 32 years of service and leadership to GSK and the industry,” stated Sir Philip Hampton, GSK’s chairman. “We will thank Andrew more formally for his tremendous dedication and contribution next year. In the meantime, we will now start a formal process to appoint his successor, whilst also ensuring the group remains focused on execution of its strategy to drive growth and performance.”