Francois is extremely familiar with Wilson, having been signed by him for Swindon after impressing in a trial.
The Haitian was part of the Robins' squad which was relegated to the fourth tier of English football in this past season, he wasn't, however, a regular starter under Wilson, making this signing a little bemusing to United fans.
On the signing of the 24-year-old, Wilson said: "Lecs will thrive on the pressure and expectation, and hopefully we will see that we have got a very good player on our hands.
"He was out of contract and we had contact from his agent, as did a lot of clubs, and we just asked him if he fancied coming in. The upside is I know Lecs very well.
"He is very athletic, has a terrific left foot, is comfortable at both left-back and centre-back, so gives you good options.
"What we will see is an aggressive and competitive character and I am very much looking forward to working with him."
The Blades boss is looking to strengthen in many areas in this transfer window, before, amidst and after United's rigorous pre-season campaign, which begins at Sheffield FC on the 9th of July.
He continued: "At this moment in time I am looking at the squad and we are very low on numbers down the left and Lecs gives us good strength in depth.
"At times I have seen flashes of a fantastic player. All he has lacked at times is a bit of consistency, but most young players struggle with that at times."
Francois, a former Paris Saint-Germain youth player, pens a two-year deal with the Blades.
Image copyright to Action Images