The 24-year-old former Penrith Panthers prop or second-rower has become the latest Leeds player to be dual-registered with the Hawks after being left out of the Rhinos team to play St Helens.
Hunslet director of rugby Darren Williams said: "Mitch is seen as a huge prospect by the champions, so to be able to include him in the lead-up to a big game on Sunday is a massive boost to the club."
Achurch is one of six Leeds players available to Hunslet, although only five can be selected at any one time.
Samoan prop Kylie Leuluai was prevented from turning out with the Hawks because of visa restrictions but Achurch is a British passport-holder.
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