Another long-serving Chief Minister of Bihar is Nitish Kumar, who is also the current CM of the state. He has been in power since 2000 but at different periods serving the state as CM for more than 16 years. First he served for just 8 days in 2000, then from 2005-2014 he served as the CM of Bihar, and again from 2015- present.

Madhya Pradesh current Chief Minister Shivraj Singh Chouhan also has been serving the state's Chief Minister for long years. It's been 16 years and 84 years of him as a CM of MP at different time periods. First he served as CM from 2005-2018 then from 2020 onwards to present day, he has been serving as state's CM.

Some other in the list are Mohan Lal Sukhadia of Rajasthan for 17 years, Pratapsingh Rane of Goa for 15 years, Sheila Dikshit as Delhi CM for 15 years, Tarun Gogoi as Assam CM for 15 years, J. Jayalalithaa as Tamil Nadu CM for 14 years, and Ashok Gehlot who is also the current Chief Minister of Rajasthan for 14 years and 170 days.

Source: wikepedia and current affairs.