The 20-year-old Brisbane fullback was chosen ahead of incumbent custodian Kalyn Ponga but knows Ponga will be hungry to reclaim his spot.
The Origin series opener in Adelaide on May 31 is Walsh's chance to put his own stamp on the No.1 jersey.
"KP is a wonderful player," Walsh said.
"This is my opportunity right now and it is mine to lose. I don't want to come in for one game and be out the next."
Maroons coach Billy Slater said he wanted Walsh to be himself and play the same football that got him in the side in the first place.
"That is my job," Walsh said.
"If I was in here doubting myself and not confident I would probably be doing Queensland and the jersey wrong. I will do whatever the team needs.Â
"What got me this jersey is taking my opportunities and come Wednesday I will express myself and be me."
Walsh said he didn't care if NSW targeted him as a rookie.
"I don't really care what the Blues do," he said.
"I am going to go out there and play football so they can do whatever they want. It is not going to faze me."
Walsh was in camp in 2021 and was set to play Game II but injured his hamstring in the captain's run. It taught him a tough lesson about getting his preparation right.
"I learned the hard way," he said.
"Being here in 2023 in the same position I am going to make sure I do everything during the week to prepare the best I can so that doesn't happen again. I definitely feel a lot more ready this time."
Walsh got the call from Slater on Sunday night and "shed a couple of tears".
"Those sorts of calls are the ones you remember for a long time. To have Billy Slater call and say you are going to play for Queensland is pretty special," he said.
"It hits a spot in your heart where not many things do. I am grateful and honoured.
"(Slater) is highly respected and it is a bonus that I can get tips off the best fullback we have probably ever seen."
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