McDonnell was most recently enjoying his third spell with Northern Premier League East Division side Worksop Town.
The forward finished the 2021/22 season with the Tigers as their highest goalscorer, scoring 18 goals in 42 appearances - his most prolific season to date.
As a result of his achievement, McDonnell claimed Worksop's Player' Player of the Year award and Media Player of the Season award.
During the 2018/19 season, his goalscoring abilities helped Worksop to claim the Northern Counties East League title and cup double, embarking on an incredible 22-game winning streak.
McDonnell has also played for Maltby Main, Retford United and Belper Town in the past.
Sheffield manager Ryan Cresswell is delighted with his new acquisition.
"[McDonnell] is a player I've been interested in bringing to The Club as soon as I walked through the door," he said.
"His work rate is infectious to others and he knows how to win at this level."
Photo credit: Sheffield FC
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