The proposal was approved at the extraordinary general meeting on Friday, the drug maker said in a filing with BSE.
The shareholders also gave approval to increase the borrowing power limit of the Board of Directors to Rs 750 crore.
Though both the companies have not revealed financial details about the transaction, the filing with BSE indicated that the acquisition cost is Rs 102 crore.
The acquisition process is expected to be completed in the next three to six months, a release from Granules India has said.
Auctus has two manufacturing facilities, an API facility at the Pharmacity in Visakhapatnam and an intermediate facility in Hyderabad. The API facility has approvals from leading regulatory agencies including the US FDA, EDQM, Health Canada, KFDA and WHO-GMP, a Granules press release had said.