He stood his ground and refused to budge on the issue of splitting the chief ministership, a stand that eventually led to the collapse of the three-decade old saffron alliance.
After outmaneuvering the BJP, Thackeray will now have to prove his credentials as a leader who can navigate a new political path with ideologically different parties like the Congress and the NCP, partners in the Sena-led ruling coalition, the Maharashtra Vikas Aghadi (MVA).
Though in politics for long, Thackeray has never contested an election or held a public post and it will be interesting to watch how he learns the ropes of governance in a state which is an economic powerhouse and home to the financial capital of the country.
The Sena, a party identified with Hindutva politics and "anti-Congressism" since its inception, has entered a new phase where it will have to chart out a new course under Thackeray in the changed political scenario.
Born on July 27, 1960 in Mumbai, Thackeray studied at Balmohan Vidyamandir and later graduated from the JJ School of Arts, where photography was his main subject.
Besides being a published author, he is also a professional photographer whose work has appeared in various magazines and has been showcased at numerous exhibitions.
Thackeray largely lived in the shadows of his legendary father before coming on his own after being appointed the Sena working president in January 2003.
Thackeray formally took over as the chief of the Sena, founded in 1966 to fight for the rights of Marathi people, after his father died in 2012.
Known for his passion for photography, he started out in the advertising field by setting up an agency called 'Chaurang'. Thackeray specialises in aerial and wildlife photography.
He has two photo books to his credit, 'Maharashtra Desh' (2010) on the forts of the state, and 'Pahava Vitthal' (2011) on the Pandharpur wari (on pilgrimage to the temple town of Pandharpur).
'Maharashtra Desh' is full of breathtaking aerial shots, providing a glimpse into the cultural fabric, physical beauty and historical perspective of this wondrous state.
A few years ago, he organised an exhibition of his photographs and Rs 10 lakh collected from their sale was donated for farmer causes.
Like former prime minister Rajiv Gandhi, who started out in politics by helping his mother Indira Gandhi, Thackeray began assisting his father at a time when the firebrand Sena patriarch was aging and the party's sphere was expanding.
He focused on strengthening the organisation and encouraged cadres to take up issues of farmers in the suicide- prone districts of rural Maharashtra.
Thackeray sought to make the Sena, known for street politics and aggressive stand on issues of public interest, more acceptable to people outside its core voter base.
After completing his journey from 'Matoshree', the Thackeray home in suburban Bandra, to 'Varsha', the CM residence in south Mumbai, the Sena leader will have to reinvent himself, according to political observers.
He will now have to display flexibility and political acumen to deal with new-found allies and keep the coalition government going for five years, they said.
"Despite being in government, the three parties are independent entities and would want to expand their respective political base," the observers said.
"A political affairs committee would be needed to identify constituencies where the Sena and the Congress-NCP are in direct contest with each other and prevail upon the local leadership to work out an arrangement where political base of the three parties remains unaffected," a senior Congress leader said.
While Thackeray has shown political sagacity and maturity till now, he will also have to deal with an aggressive BJP in the opposition knowing very well the former ally will try to make functioning for his government difficult, the observers said.
"Uddhav will have to keep his flock of MLAs together," they said.
Over 20 years ago, Thackeray was seen as a 'reluctant' politician, living a cosy life with his wife Rashmi and sons Aaditya (now an MLA) and Tejas at 'Matoshree'.
But now that he has taken plunge into governance and managing a disparate coalition, a slew of challenges await Thackeray, who will be one of the most closely watched politicians in the country in these media-driven times.
Since the Sena leader is currently not a legislator, he will have to get elected either to the legislative assembly or the council within six months of taking oath.
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