The business association said that Mr Overmyer was retiring as part of its planned succession.
The American will be leaving Singapore at the end of June for his new home in Texas in the United States.
SICC said that Mr Overmyer will assume the role of senior adviser to its board. Asked the specific areas in which Mr Overmyer may be required to provide counsel on, an SICC spokesman said that this will be at the discretion of the board.
Speaking to The Business Times yesterday, Mr Overmyer said that his decision was purely a personal one as he and his wife wanted to spend time with their newborn grandchild in Texas.
Acknowledging that the decision may seem sudden, he said that he had made his decision known to the board about a year ago. "They (the SICC board) said that they were going to get someone else to do the work, but they didn't," he said, adding that it was difficult for the board to find a suitable and qualified replacement.
The board has appointed Victor Mills, currently chief operating officer at SICC, as acting chief executive. Mr Overmyer said he was unclear if this was an interim appointment and if the board was still on the look-out for another candidate.
Although he said that Mr Mills was "not fully established" at the job yet, SICC is making arrangements to give him the support he needed, including having two or three senior board members guide him.
"Until I leave in about a month and a half's time, I will stop playing the big shot and we will get him (Mr Mills) to play the big shot and we will see how it turns out," Mr Overmyer said.
Mr Overmyer, who is in his mid-60s, said he had no plans where work was concerned and was content to travel the US and spend time with his family.
Although he said that he was happy with his time at SICC, during which the chamber achieved "some tremendously good things", Mr Overmyer regretted not being able to be in Singapore for the celebrations to mark the Republic's 50th year of independence next year. "It is something that I have been doing some work on of late and I wished I would be here to see that through or to be a part of the celebrations," he added.
Mr Overmyer became chief executive of SICC in 2003 after a career spanning almost three decades in the telecommunications industry, including 12 years here. He was previously vice president of global services for AT&T in Asia and vice president of Samuels International, a Washington DC-based international consulting firm.
He has also served as a board member at SICC and was chairman of the board from 1996-1998.
"As chief executive, he has become the public face of the chamber. He is very well known and respected in the business and government circles alike," noted Rolf Gerber, chairman of the SICC board, while thanking Mr Overmyer for his services to the chamber.