Dhir was also backed by the lone JD (U) MLA and an Independent.
37 MLAs supported Dhir while BJP candidate Jagdish Mukhi got the support of 32 MLAs from his party.
Immediately after his election to the post, Chief Minister Arvind Kejriwal and BJP leader Harshvardhan greeted Dhir and wished him good luck.
"I congratulate you from the core of my heart and hope that you will keep the prestige and the tradition of the assembly intact," said Vardhan.
The pro-tem speaker conducted a voice vote twice following objections by BJP MLAs.