This is Amat's second term as Speaker, as he also held the post during the Biju Janata Dal's third term.
Deputy Speaker Sanand Marandi announced Amat as the Speaker after a voice vote.
A motion was moved by BJD on Monday before the Assembly Secretary to elect Amat for the Speaker and a special session convened on Tuesday where Chief Minister Naveen Patnaik moved a resolution for Amat's election and Parliamentary Affairs minister Bikram Arukh seconded it.
Following his election, Amat told reporters: "I will ensure a congenial environment for the smooth functioning of the Assembly by maintaining a cordial relationship with all the members of the House."
The election was necessitated following the resignation of incumbent Niranjan Pujari, who was inducted in the cabinet during the recent ministerial reshuffle.
Amat has so far been elected to the Assembly from Boudh constituency four times - as an independent candidate in 2000 and as BJD candidate in 2004, 2009 and 2014.
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