Poleon has linked up with Danny Wilson’s side on loan until the end of the season and his deal will also allow him to feature in the play-offs if the Blades fall short of automatic promotion.
The spell is Poleon’s second away from Elland Road this season and his move comes three weeks after he agreed a new contract with Leeds.
The 19-year-old made his senior debut in August but was sent to Bury before Christmas and Warnock has allowed him to move out temporarily again, despite insisting previously that Poleon would only be made available if another attacking player was signed.
Warnock said: “He’s got to play regularly and keep his position but he’s getting better in training.
“It’s a good opportunity at Sheffield United and a good club for him to go to. They’re doing well and he should be able to play with confidence. We’ll have the opportunity of having him back in 28 days if we need him.”