Meanwhile, executive vice-president Gene Delaney has said the firm will try to reclaim the title of top handset maker in China.
Galvin said in a statement that he's stepping down because he does not "share the same view of the company's pace, strategy and progress at this stage." The statement did not provide additional details on the reason for the departure. A Motorola representative was not immediately available for further comment.
The company's presiding director, John Pepper Jr, said in a statement that Galvin will remain in the top slot at the No. 2 mobile-phone maker until a replacement is found. Galvin also will take part in the executive search process, Pepper said.
Speculation about Galvin's replacement began within moments of the announcement. Among the early favourites are Mike Zafirovski, Motorola's president and chief operating officer.
Galvin has worked for Motorola for 36 years. He has been the company's chief executive officer since 1997, experiencing a reign in which he was criticised by analysts for not spinning off Motorola's semiconductor or cellphone divisions once they began experiencing less demand. Also under his leadership, Motorola was overtaken by Finland's Nokia as the world's No. 1 handset maker.
Galvin said he's leaving about halfway through a five-year turnaround plan he devised for the company, which has been plagued by slumping industry demand for new cellphones.
"It is time for me to pass the baton to new leadership," Galvin said in a statement. "I leave my successor with a formidable Motorola platform compared to three years ago."
In China, the firm will continue to reduce costs and ramp up product releases to increase competitiveness, Motorola's executive vice-president Gene Delaney said in a China Daily report.
He also expects Motorola to improve its position by increasing its investments in local design and engineering programmes, and by accelerating distribution through stronger cooperation with its partners.
"We are going to introduce about 17 to 22 kinds of new handsets into the Chinese market in the later half of this year and next year," Delaney said in the report.
Motorola posted a quarterly profit in July, but its sales have decreased in the face of intense competition in the Chinese phone market.
Recently, domestic communication products maker Ningbo Bird unseated Motorola to become the number one handset supplier in China, reported official news agency Xinhua.
The Zhejiang province-based company garnered a slim lead with 15 percent of the market share in the first half of this year, while Motorola followed in second place with 14.2 per cent, according to figures from the country's Ministry of Information Industry.
Last year, China accounted for about 14 percent of Motorola's sales.
As yet, the company has not found a replacement for Motorola China's former president Timothy Chen, who left to head Microsoft operations in China, said a report by news Website sina.com.
The firm is still vetting candidates for the position, said Delaney, who was himself appointed board chairman of Motorola China in August shortly after Chen's departure. His portfolio includes some of Chen's former duties.
Chen started on 1 September as chief executive for Microsoft's Greater China region.
