The 69-year-old, who won the World Cup in New Zealand in 2011, assisted Argentina in the Rugby Championship in 2013.
Henry and McFadden know each other on a social level but have never worked together in a professional capacity.
Henry will assist the struggling Warriors side in the hope of improving their skillset but more importantly providing support and mentorship to McFadden and his backroom staff.
“We’ve had some healthy discussions about coaching previously and I’m thrilled to have the chance to be able to work with him, to observe the organisation and to provide some feedback,” Henry told Fox Sports.
The Warriors’ anaging director Jim Doyle along with McFadden are the driving forces behind seeking to utilise Henry’s vast experience in a bid to boost the side’s structures.
“I’ve always been open to the idea of having extra support to help me to develop and improve,” said McFadden.
“Jim and I have considered a number of options but it was important to take time to find the person who best fitted the position and was available to help.”