He participated in the Ship for Southeast Asian Youth Program (SSEAYP) as a Participating Youth (PY) in 2004 and the National Leader (NL) of Cambodia contingent in 2012. One of the pioneering members, he joined the Executive Committee of SSEAYP International for the 2005-2006 term as the Public Relations Officer. Kimlee is a respected leader for his longest serving executive leadership in SSEAYP International Cambodia. Over the course of 18 years, he held the office respectively as Secretary General for 2 terms, Vice-President for 2 terms, and President for 2 terms. He has had his involvements in all the major historical events such as SIGA 2007 & 2016 , SSEAYP’s Country Port-of-Call in 2014 and 2017, and SSEAYP Library Construction Project in Domnak Raing Commune of Kompong Speu. He remains the prominent Advisor to President (AP) in the 2023-2024 term. Having graduated with a Master degree in Business Administration from University of Wales, UK in 2011, Kimlee is also the Deputy Secretary General of National Youth Development Council.