The Maroons left out incumbent Newcastle fullback Kalyn Ponga, who was set to be selected before leaving the field in the Knights' 26-6 loss to Cronulla on Saturday with an HIA.
Ponga passed the concussion test, but due to his series of recent concussions the Maroons have put his welfare first and rewarded Walsh for his stellar form for the Broncos.
In another selection bombshell, Maroons regular Dane Gagai has been dropped and his centre spot given to Dolphins fullback Hamiso Tabuai-Fidow, who made his Origin debut in 2021 in the centres.
Newcastle's Gagai struggled defensively against the Sharks on Saturday while Tabuai-Fidow has been brilliant for the Dolphins.
Gold Coast second-rower David Fifita has won a recall and is set to start alongside Dolphins lock Tom Gilbert in the back-row.
Brisbane second-rower Kurt Capewell suffered a shoulder injury in the 15-4 loss to Penrith on Thursday night and has been left out.
The Maroons' plans for the series opener on May 31 in Adelaide were thrown into disarray during round 12 of the NRL.
Dolphins second-rower Felise Kaufusi, who was a certainty to be selected, was charged by the match review committee for a high shot on Christian Welch in the Dolphins' 24-16 loss to Melbourne.
He is facing a three-week ban.
Brisbane prop Tom Flegler has also earned a recall and will play his first game for the Maroons since his solitary appearance in 2021.
Walsh and Tabuai-Fidow have both won their selection on form.
"They have been brilliant and both have done a great job for their clubs," Slater told AAP last month.
Walsh has been brilliant in attack for the Broncos but it is his improved defensive clout that proved integral in his selection.
"Reece is putting his body on the line and being courageous," Slater said.
"He is starting to get himself into good positions defensively as well and when you get that part of your game sorted you can help your team get in really good positions defensively.
"I see growth in both (Tabuai-Fidow and Walsh) in that area."
Queensland: Reece Walsh, Selwyn Cobbo, Valentine Holmes, Hamiso Tabuai-Fidow, Murray Taulagi, Cameron Munster, Daly Cherry-Evans, Tom Flegler, Ben Hunt, Lindsay Collins, Tom Gilbert, David Fifita, Pat Carrigan. Interchange: Harry Grant, Tino Fa'asuamaleaui, Reuben Cotter, Jai Arrow. Reserves: Tom Dearden, Christian Welch.
18°C