It was almost 18 months ago that Katich announced he was quitting NSW and the state game in Australia.
But WA have secured the services of Katich to provide an experienced head for their young squad despite unsuccessfully trying to lure him back in the past.
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The 38-year-old's return isn't expected to extend to Sheffield Shield cricket, but after scoring 1000 runs at 73 in county cricket this year, Katich will be a handy addition to his native state side, even for a four-match stint.
The one-day cup suits Katich because the entire tournament is being staged in Sydney where he resides.
Western Australia start their one-day campaign against Queensland on Friday at Bankstown Oval, with Katich named in their 16-man squad that also includes Shaun Marsh.
Warriors coach Justin Langer said Katich would add valuable experience.
"We've got a great opportunity with Simon Katich here to provide some real leadership for the group, Langer said.
"He has agreed to play the final four matches of the Ryobi one-day cup which presents a fantastic opportunity for our young guys to rub shoulders with and learn off someone with his experience and knowledge of the game.
"We've seen the example of Ricky Ponting at State level and we hope Kat can have a similar impact on our group."
Katich, who has captained the Perth Scorchers for the past two Big Bash seasons, returns to the Western Warriors set-up for the first time since 2002 when he left to join NSW.
Marsh has been named in the squad despite suffering a hamstring injury while with the Australian team in England last month.
Michael Beer will captain the side in the absence of Adam Voges who, along with Nathan Coulter-Nile and Mitchell Johnson, is absent from the squad due to international commitments with the Australian limited-overs team in India.
Langer said Marsh's availability still remains subject to fitness testing in Sydney.
"We're hopeful and we will be monitoring him closely," Langer said.
"His rehabilitation has been meticulous so we'll be seeking medical advice on his availability."
Warriors squad: Ashton Agar, Cameron Bancroft, Michael Beer, Jason Behrendorff, Hilton Cartwright, Burt Cockley, Ryan Duffield, Marcus Harris, Simon Katich, Shaun Marsh, Marcus North, Nathan Rimmington, John Rogers, Ashton Turner, Andrew Tye, Sam Whiteman.