The Supreme Court of British Columbia had granted the final order for the acquisition on April 6, Drax said.
This meant all the conditions to complete the acquisition had now been satisfied or waived, it added.
Drax and Pinnacle shareholders have approved the transaction.
Pinnacle Renewable Energy produces sustainable fuel for renewable electricity generation and the deal values the company at C$741 million ($588 million) including debt.
($1 = 1.2606 Canadian dollars)
(Reporting by Nora Buli; editing by Jason Neely)