Prime Minister Narendra Modi tweeted his congratulations to Fadnavis minutes after the swearing-in ceremony
The poll victory in Maharashtra for India's main ruling party was not as decisive as it was hoping for.
He also dismissed charges that there was delay on part of the Congress to form government in the state with the Shiv Sena and NCP.
In a series of tweets, Congress spokesperson Randeep Surjewala hit out at the BJP, accusing it of taking a "contract to kill" democracy in India.
The oath was administered by Maharashtra Governor Bhagat Singh Koshiyari
The month-long political impasse ended dramatically with Devendra Fadnavis returning as the chief minister again, backed by the Sharad Pawar-led NCP
Shah tweeted his congratulation to Fadnavis and NCP leader Ajit Pawar, who was sworn in as the deputy chief minister, after the oath-taking ceremony
Following weeks of bitter political drama, the Sena is currently in the process of forming a non-BJP government
On Patil's remark, Malik questioned why the BJP did not form a government earlier if it had the numbers as claimed by its Maharashtra unit chief.
The former CM put forward the demands when he called on Koshyari at Raj Bhavan in the morning.
The Sena alleged that protocol was not followed when it went to the Raj Bhawan to seek more time to stake claim for government formation
Former Maharashtra chief minister Devendra Fadnavis on Tuesday changed his Twitter bio to 'Maharashtra's Sevak'
The President signed the notification following the recommendation of the Union Cabinet which acted on the report from the state Governor Bhagat Singh Koshyari
Jayant Patil said the party would discuss the issue with its ally, the Congress, and get back to the governor by or before 8.30 pm on Tuesday
Khattar and Chautala will take oath of office on Sunday afternoon while in Maharashtra fight for CM's position continues between BJP and Sena
The BJP and Shiv Sena negotiations are now somewhat reminiscent of their post-election government formation negotiations in 2014
Fadnavis and Thackeray traded charges over power-sharing arrangement at their respective news conferences shortly after the BJP leader drove to Raj Bhavan and handed over his resignation to Governor
Governor Bhagat Singh Koshyari on Saturday evening asked the BJP, the single largest party in the new Assembly, to 'indicate the willingness and ability' to form government
Sanjay Raut in a tweet said, 'Jo khandaani raees hain wo mizaj rakhte hain narm apna, tumhara lehja bataa rahaa hai, tumhari daulat nayi nayi hai'
As no party had come forward to form the government, the governor decided to explore the possibility of formation of government on Saturday