Mason suffered a wrist injury during last weekend's 2-1 defeat at Warrington Rylands.
Following further assessment, he will now be forced to sit out the remainder of the 2022/23 campaign.
Mason joined the Lions on loan from Southport before Christmas, and subsequently completed a permanent move to the club at the end of January.
He has featured regularly for Guiseley since his arrival, making 16 appearances in total.
They are currently 10 points adrift of the play-off places following Saturday’s surprise 1-0 defeat at home to struggling Belper Town.
Photo credit: Guiseley
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