He arrives at the Sheepicorns having helped his former club to a 16th-place finish in the NCEL Premier Division last season.
He will go straight into contention for their opening pre-season friendly away at Penistone Church this Friday.
Ossett United joint manager Mark Ward said: “We are happy to get this deal done. We tried to sign TC last season, but he chose to be loyal to AFC Mansfield as he was the captain there.
“He has fitted in really well, is keen to learn and he looks extremely fit.”
On his arrival, Cropper added: “I’m ready for the step up in level. I know it’s going to challenge me but I’m up for the challenge ahead. The lads are a great bunch and I’ve noticed a difference in the standard just in training.
“Both Jas [joint manager Jas Colliver] and Wardy have high standards - the training has been tough but enjoyable.
“I’m looking forward to the games coming up now and meeting the fans that the lads keep talking about.”
Meanwhile, the club have also confirmed that right-back Prince Attakorah has penned new terms ahead of the 2022/23 season.
Attakorah, formerly part of Rotherham United’s academy, impressed at Ingfield last season.
Photo Credit: Ossett United
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