Malaysian High Court sentenced Manimaran, 24, S Saravanan, 29, and K Perumal, 31, for killing Sindambaram on January 11, 2009 when they entered his house in a robbery bid.
The Judicial Commissioner Teo Say Eng issued the mandatory death penalty for the trio for murdering the 64-year-old Ipoh Barat MIC division treasurer.
Earlier, Teo had convicted the men, saying the prosecution had proven its case beyond reasonable doubt.
Sindambaram was also the chairman of the Ipoh Hindu Devasthana Paripalana Sabah, which manages the Sri Maha Mariamman temple and the Sri Subramaniar Temple.