The 29-year-old will be awarded the FOGS Dick 'Tosser' Turner Medal after the series opener on Wednesday night, in honour of the late and legendary former team manager regarded as the godfather of the Maroons.
Queensland skipper Daly Cherry-Evans (25 games) is the only other Maroon in the current team to have been awarded the medal.
"It means everything to me," Holmes told AAP.
"You want to wear the jersey once but to do it 20 times is very special. It makes me feel old in one way but it is also very humbling. I can't wait. I think of the great players that have played 20 Origins and it is not an easy task. I am grateful and honoured.
"Ben Hunt last year played his 20th and we had a chat about what (Turner) meant for the state and this team. It is pretty cool how the Maroons honour people of the past who have done so much for this jersey."
Holmes is the third-highest tryscorer in State of Origin history with 13, behind Greg Inglis (18) and Darius Boyd (17).
Incredibly nine of those tries have come from his eight matches on the wing, rather than at centre where he plays club footy for St George Illawarra.
Holmes was going to play in the centres in game one until injuries on the cusp of the team being announced forced a change by coach Billy Slater, with Sydney Roosters rookie Robert Toia thrust into the position.
"Selwyn Cobbo hurt his wrist when we played the Broncos and Bill called me and said that I would have to make the change after Murray Taulagi had also done his calf," Holmes said.
"I feel like I am a specialist on the wing as well so it's not like it is a foreign position for me. I was just glad I wasn't getting the call to say they weren't going with me. For me it just means that I probably get to score another try or two. Nothing changes.
"I will play my heart out and do all I can for this team and jersey in my 20th game."
The 2016 premiership winner made the move from North Queensland to the Dragons this year and has built into top form.
"Coming into a new team it probably takes a bit of time to get used to," Holmes said.
"We have a new spine with Clint Gutherson and Damien Cook and a real camaraderie as well.
"I feel like we have had good moments where we have beaten Melbourne and Brisbane but then we have lost three games by one point, which is disappointing because if we win two of those we are sitting in the top eight.
"With the team around me I feel happy. I am excited to go to training and when I am out there playing I am running around with a smile on my face whether we win or lose. We have a tight-knit group and there is something building."
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