Here is your ten-point cheat sheet on this big story:
Bhupendra Patel, 59, was the choice of both PM Modi and Union Home Minister Amit Shah, and is a protege of former Chief Minister Anandiben Patel.
Amit Shah and some BJP chief ministers are expected to attend the oath ceremony.
Vijay Rupani was present when Mr Patel was selected leader of the BJP legislature party on Sunday, preceding the new Chief Minister's oath ceremony.
Mr Rupani said the party will "successfully contest the polls" under Mr Patel's leadership.
Mr Patel, the BJP MLA from Ghatlodia seat held earlier by Anandiben Patel, was an unexpected choice after much speculation circling around two other names - Union Ministers Mansukh Mandaviya and Parshottam Rupala.
The names of controversial Lakshadweep administrator Praful Khoda Patel and Gujarat minister RC Faldu were also in circulation.
Mr Patel, who has a diploma in civil engineering, has been a member of the Ahmedabad Municipal Corporation and the Ahmedabad Urban Development Authority. He won the 2017 Gujarat election by a record margin.
Vijay Rupani became the fourth Chief Minister to be replaced in BJP-ruled states this year. His handling of the second wave of Covid and his style of functioning are believed to be among the factors that drove him out. He was reportedly also perceived as too soft and ineffective.
Another reason for his replacement by Mr Patel is poll math. Mr Patel's appointment is meant to mollify the powerful Patidar community, which has been upset with the BJP and has backed the opposition Congress's Hardik Patel.
Mr Rupani's exit mirrored his own takeover in 2016- 16 months ahead of elections- after Anandiben Patel was removed as Chief Minister.
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