Speaker B B L Butail administered oath to Dhiman in his chamber in the presence of leader of the opposition, P K Dhumal, state BJP chief Satpal Singh Satti and other party MLAs.
The by-election was held following the death of veteran BJP leader, a six-time MLA and former minister, Ishwar Dass Dhiman in November last year. Anil is his son.
The election was held on April 9 and result was declared on April 13.
The BJP has claimed that Dhiman's victory was a trend setter and the party would return to power after assembly polls in November this year.