Gujjar, 54, was elected unanimously on the first day of the new Haryana assembly's sitting.
He was escorted to the speaker's chair by Haryana Chief Minister Manohar Lal Khattar, former chief minister Bhupinder Singh Hooda, Indian National Lok Dal (INLD) leader Abhay Singh Chautala and others.
Elected from Jagadhri assembly constituency on a Bharatiya Janata Party (BJP) ticket, Gujjar is a graduate.
All newly elected legislators, except one, in the 90-member house were Monday administered oath of membership by pro-term speaker Raghuvir Singh Kadian. This is the 13th assembly for Haryana, which was formed Nov 1, 1966, carved out from the Punjab state.
Khattar was the first to take oath.
Majority of the members took oath in Hindi while some in English and Punjabi. Finance minister Abhimanyu took oath in Sanskrit.
This is the first time that the BJP has got a majority on its own in the Haryana assembly. The party won 47 seats in the Oct 15 assembly polls.
The INLD won 19 seats while the Congress, which remained in power from March 2005 till Oct 2014, managed only 15 seats.