The 30-year-old will honour the heritage of his mother Lucy Holmes and make himself available for the Aitu at this year's tournament, to be hosted by Australia and Papua New Guinea.
Holmes is yet to play for the Cook Islands. He had a rotator cuff injury at the end of last year and missed the Pacific Championships and World Cup qualifying 58-6 win over South Africa that secured the 10th and final spot for the Aitu at the global tournament.
While Holmes did not play in those games, on the invitation of coach Karmichael Hunt he joined the squad ahead of the South Africa clash in a mentoring and coaching role.
That included a trip to Rarotonga so the players could reconnect with their culture and understand who they were playing for.
Holmes had his best game of the season for the Dragons on Sunday when his two tries and elusive runs secured the side a 30-26 upset win over Brisbane, their first victory of the season.
The performance put him back in the frame for a Maroons recall, for whom he has played 22 times and with distinction.
Post-match he said he "definitely" would be available for the Aitu at the World Cup.
"I've been very fortunate enough and lucky to wear the Aussie jersey 21 times and I played in a couple of World Cups, Four Nations, and ANZAC Tests," he said.
"Now I want to give back to my mum's side and to my culture's side.
"She's obviously over the moon, and she's one of 12 (children) so they're all very happy to see me hopefully play at the end of the year. Touch wood I can make it there.
"We'll see what happens facing some quality teams too."
Cook Islands have a strong playing list which includes Cronulla centre KL Iro, Brisbane premiership winning second-rower Brendan Piakura, Warriors hardman Marata Niukore and Melbourne prop Davvy Moale.
They have a tough draw at the World Cup and will play Fiji, New Zealand and Australia in the group games.
The proud Pacific nation has competed in three World Cup competitions, in 2000, 2013 and 2021. They failed to progress beyond the group stage but beat Wales 28-24 in 2013 and 18-12 in 2021.
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