National Volunteer and Philanthropy Centre (NVPC) chief executive Laurence Lien will not be seeking to extend his term as a Nominated Member of Parliament (NMP) when it ends in August.
Responding to queries from The Straits Times, Mr Lien said he thought it appropriate to "pass on the baton" to another leader in the social sector to advocate social causes.
"I have had my opportunity to champion social causes, and I think it is time for me to let others have a chance," the grandson of the late banker and philanthropist Lien Ying Chow said in an e-mail.
"Since I am intending to step down from my full-time position at NVPC, I also think it is appropriate for me to pass on the baton to another social sector leader who can more fully represent the sector."
Mr Lien, 43, indicated last year he was intending to step down from his position as NVPC's chief executive, a post he has held for almost six years.
Joining the Budget debate in Parliament on Monday, he had prefaced his speech by saying it would be his last.
"I would like to thank the Deputy Prime Minister and Finance Minister not just for a thoughtful budget speech, but also for being a champion of inclusiveness," he had added.
In February 2012, he was among nine NMPs appointed by the President, on the recommendation of a selection committee chaired by the Speaker of Parliament.
These non-partisan individuals' serve a term of two-and-a-half years, though some NMPs have been known to stay up to three terms.
Mr Lien, a strong advocate for social issues, has spoken extensively in Parliament on the need to support vulnerable groups such as the poor, elderly and the disabled who may otherwise fall through the cracks.
Last March, he criticised current approaches used to help the poor, which he said stripped them of their dignity. Aid schemes, he added, should look at root causes and the needs of people, beyond just looking at their income levels.
In another speech, he also called for a reset of social and economic policies in order to develop a more vibrant and diverse society, as well as a more productive and entrepreneurial economy.
During the 2012 Budget debate, he said Singapore was in a social recession - individuals were less resilient, family ties had loosened and the community was less cohesive.
