The state's largest independent fuel company, Gull Petroleum, has been acquired by Archer Capital-backed Ausfuel for an undisclosed sum.
Gull, was founded in 1976 and consolidated into the Rae family ownership in 1984.
It has nearly 100 service stations across WA.
Ausfuel is a Northern Territory-based fuel and logistics business that was founded 25 years ago in the NT.
"We're delighted that the tradition of independence and Australian ownership so important to Gull will continue with the acquisition by Ausfuel," said Gull chairman Neil Rae.
Ausfuel CEO Brooke David said his group was delighted with the new acquisition and saw many opportunities for growth in the Gull business.
"It's a well known and well loved WA brand," said Mr David.
"We're proud to have it as part of our group.
"We intend to invest, renew, upgrade and grow the Gull business and offer more to our customers,'' Mr David said.
He said Gull will continue to operate as a stand-alone business focused on WA.
Mr David said all of Gull's fuel supply, terminalling, fuel delivery and customer support arrangements will continue.
Gull Petroleum's total revenue in 2009-10 was $895 million.