Robertson won his only two Australian caps in friendlies in 2023 and his exile from the national team set-up prompted fears he may declare for one of the three other nations - England, Peru and Scotland - he also qualifies for.
The 22-year-old midfielder was part of the Socceroos squad but did not play for Graham Arnold's side in a friendly against England at Wembley in October 2023 and has not turned out for Australia since.
When he replaced Arnold, current Socceroos boss Tony Popovic said a paperwork issue had prevented the Cardiff youngster from receiving a call-up.
Robertson eventually returned to the Socceroos fold last October and did not take the field.
But he appears firmly locked in for Australia ahead of Friday's friendly against Cameroon at Accor Stadium with hopes of nabbing a spot on the plane for this year's World Cup in North America.
"I wasn't actually too sure what it (the paperwork issue) was, I just let other people deal with that, sort it all out and it all got sorted," Robertson said on Tuesday.
"I'm actually not too sure what the issue was at the time, I can't remember.
"There was never any real thought to go anywhere else, it was always Australia.
"I grew up in Australia as a kid and classed myself as being Australian and I couldn't think of playing for any other country, even though I played (youth football) for England because I was over there.
"I think those rumours, I've seen a few of them, it was kind of just paper talk."
Robertson's decision to go all-in with Australia is a win even if the midfielder, who has scored five goals and accumulated two assists this season, is playing in England's third tier.
Cardiff are on track for automatic promotion to the Championship and Robertson's commitment comes at a time when Adrian Segecic (Croatia) and Nectar Triantis (Greece) have turned their backs on the Socceroos.
Sydney-born Cristian Volpato of Serie A side Sassuolo recently met with Popovic but appears to have reneged on any plans to pledge his allegiance to Australia after telling Italian media over the weekend he only had eyes for the Azzurri.
Socceroos captain Mat Ryan said he would never close the door on any dual-eligible player returning to the set-up and pointed out Australia had enjoyed a good run of pinching players with split allegiances.
"I don't like confrontation and I respect everyone's decision, of course," Ryan said.
"If you get to a point where a player like that would come in here then you go ahead and accept them and just try to make the team as strong as possible.
"We've had players like Martin Boyle in the past who have been on the other side and changed allegiance to us."
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