Sydney FC coach Graham Arnold has been named as long-term Socceroos boss on Thursday.

In Australian football’s worst-kept secret, Arnold will take over from Dutchman Bert van Marwijk after the World Cup in Russia and is expected to see Australia through until the 2022 World Cup.

That will include the Socceroos’ Asian Cup defence in the United Arab Emirates next January.

Arnold has long been a favourite for the role on the back of his record-breaking success with the title-winning Sky Blues.

The 54-year-old will leave the A-League club at the end of the season to return to the national team set-up for the first time since coaching the Socceroos for 12 months following the 2006 World Cup.

Arnold has accepted a four-year contract with Football Federation Australia which starts in August and includes the 2022 World Cup, should the Socceroos qualify.

Arnold, 54, previously coached the national side in 2006-07 and was an assistant coach with the Socceroos in 2008-10, before accepting the head coaching role with A-League club Central Coast Mariners.

He switched to Sydney FC in the 2014-15 season and led the Sky Blues to the Premiers Plate and grand final victory in 2016-17.

The announcement came hours after Sydney was dealt a near-fatal Asian Champions League blow, losing to group opponents Kashima Antlers 2-0 at Allianz Stadium.

Arnold’s team had been considered Australia’s best chance of winning Asia’s flagship tournament since Western Sydney lifted the 2014 trophy.

Sydney FC compete in the return fixture in Kashima on Tuesday.

“My commitment to Sydney FC is 110 per cent to the end of this season,” Arnold said in Sydney.

“It (the Socceroos job) is obviously a tough job but one I’m really excited and look forward to.”

Arnold was the first to say he’d learnt from his mistakes in his first incarnation as Socceroos coach nearly a decade ago, taking in 2007’s failed Asian Cup.

“Obviously I’ve made plenty, but I’m a person who learns,” he said.

“I’ve been heavily involved with the Socceroos for a long, long time … so I know what the job is about.

“It’s not an easy job but I know I’ll do a great job this time and I feel definitely that I’m ready.”

Arnold said the specifics of backroom staff had not yet been decided, though it’s rumoured highly-respected Sky Blues conditioning coach Andrew Clark and video analyst Doug Kors would follow him into the national set-up.

-with AAP