The majority of Drillseach shareholders threw their support behind a merger with rival Beach Energy.
Nearly 94% voted in favour of the shake-up.
Drillsearch chairman Jim McKerlie said: “The focus of both companies is to press ahead with implementation of the proposed merger and to successfully integrate the two businesses to drive value from the combination.”
Beach Energy is not required to seek approval from its shareholders for the deal.
Beach Energy has weathered two major writedowns in the past six months, forcing it to shoulder impairment charges of $650million.
A court hearing on February 18 is the next step in the approval process.
The deal is expected to be implemented by March.