Warnock was ready himself to start talks with Saints boss Steve Wigley on Monday hoping to sign the 27-year-old former Blackpool forward.
However, the Blades boss revealed Ormerod has snubbed any chance to go to Bramall Lane in favour of a move to Elland Road.
"Steve (Wigley) told me that Ormerod was going to Leeds and I am very disappointed," Warnock told The Blades official website.
"Perhaps I should have talked to the player first but it's a lesson for me even at this stage of my career. Perhaps I shouldn't do things legally."
This could make up for us missing out on Barry Hayles, who snubbed us for Sheffield United in the summer. And what a success that was!