Chamling's Sikkim Democratic Front won two thirds majority in the Assembly elections winning 22 of the 32 seats with a vote share of 55 per cent.
He won both from Rangang-Yangang and Namchi-Singhithang assembly constituencies with huge margins.
Chamling took over the reins of the state on December 12, 1994 and completed 20 years as chief minister of the Himalayan state.
He is set to break the record of late Communist leader Basu considered the longest serving chief minister for more than 23 years from June 21, 1977 to November 5, 2000 in West Bengal.