Kerala Congress(M) chairman and former state finance minister KM Mani's last journey began on Wednesday morning.
The body of Mani, who died on Tuesday at the age of 86, was taken to Kottayam, the centre of his political activities for many decades.
Hundreds of people gathered at the main towns en route to Kottayam, through which the body was taken in a state-owned bus, and paid their last respects to the departed leader.
Mr Mani's body would be kept at the historic Thirunakkara maidanam in Kottayam, the Kerala Congress(M) state committee office and his village Marangattupilly, before being taken to his hometown Pala in the evening.
The funeral would be held at the St Thomas Cathedral in Pala on Thursday afternoon with full state honours.
Mr Mani died at a private hospital on Tuesday evening while undergoing treatment for pulmonary disease.
The Kerala Congress(M) leader, who had been the MLA of Pala for 54 years without a break till his death, is survived by wife and six children, including Kerala Congress(M) vice-chairman and Rajya Sabha MP Jose K Mani.
The former finance minister had created history by presenting 13 budgets in the Kerala Assembly.
Prime Minister Narendra Modi, former prime minister Manmohan Singh, Kerala Governor P Sathasivam, Chief Minister Pinarayi Vijayan, state Assembly Speaker P Sreeramakrishnan, Congress leader K C Venugopal and state BJP president Sreedharan Pillai were among the leaders who condoled Mr Mani's death.