In 2007, he became the Chief of PKR's youth wing after the leader,
Mohamad Ezam Mohd Nor, left the post in 2006, and he defeated Hasmi Hashim in the 2007 election to replace him. In
2004 election, he contested the newly created Tangga Batu parliamentary constituency in his home state, Malacca but lost to
Idris Haron. Then in the
2008 election, he contested and lost the Dungun parliamentary seat in
Terengganu. He was finally elected to federal Parliament in the
2013 election for the seat of Bukit Katil, defeating heavyweight opponent, the
Chief Minister of Melaka,
Mohd Ali Rustam. In the
2018 election, he managed to retain his Bukit Katil which had change to
Hang Tuah Jaya after the 2018 re-delineation but lost the Rim seat of the
Malacca State Legislative Assembly. In 2014 he was elected a vice-president of PKR, alongside
Rafizi Ramli,
Nurul Izzah Anwar and
Tian Chua. He did not re-contest the leadership of PKR's youth wing. On 11 December 2013 Shamsul Iskandar was charged with being responsible for
Malaysia's Post General Election rally 2013 or "Blackout 505", a rally that was held in a restricted area at the compound of University of Malaysia's Ar-Rahman Mosque which happened across 15 cities in Malaysia. After five years he was acquitted on 16 May 2018 and all charges were dropped on grounds that prosecutor failed to prove the case against Shamsul beyond reasonable doubt. Following the victory of
Pakatan Harapan in 14th General Election, he was appointed as the Member of Cabinet assuming the role of Deputy Minister of Primary Industries under the new government led by Prime Minister, Tun Dr
Mahathir Mohamad. At the international level, Shamsul Iskandar is also a Board Member of
The Parliamentary Network on the World Bank & International Monetary Fund. In the 15th General Election, Shamsul Iskandar challenge Ahmad Zahid Hamidi for the Bagan Datuk parliamentary seat. He lost and later claimed he were advised against doing recount in order to allow unity government to form. == Controversies and issues ==