Millard will leave his role as National High Performance Manager at USA Rugby to make a return to Blues in the new position next month and work alongside Director of Rugby Mark Hammett.
Cardiff Blues have also announced that Richard Hodges has been promoted from his position as Academy Manager to take on the role of Elite Performance Pathway Manager.
New Head of Elite Performance Millard previously enjoyed a spell as Backs Coach at Blues between 2008 and 2010, helping the region reach the semi-finals of the Heineken Cup and win both the EDF Energy Cup and Amlin Challenge Cup.
He has a vast experience of coaching having also worked in Australia and Ireland with roles at Melbourne Rebels, Connacht Rugby, Sydney University and the Australia Sevens team.
The newly created Head of Elite Performance role will see Millard take the lead on contract renewals, player recruitment, release and retention, help control the budgets within the rugby department and attend all relevant WRU meetings on behalf of the region.
Richard Holland, Chief Executive at Cardiff Blues, said: "We're delighted to welcome Billy back to Cardiff Blues and I know he is very excited to return to Wales and take on this key role at the region.
"This is a new position which Mark Hammett identified and was very keen to see put in place. The role will involve pulling together all the elements of the rugby pathways and recruitment strategy.
"We conducted an extensive worldwide search to fill this position and had a very high calibre of applications. However, Billy was the outstanding candidate given his knowledge of professional rugby, vast experience and understanding of Welsh rugby and our region."
Billy Millard said: "I'm very excited to be returning to Cardiff Blues at such an exciting time for the region with ambitious and extensive plans for the future.
"Blues have identified how the region needs to move forward over the coming years to be a success and I'm relishing my new position within that environment.
"I'd like to take this opportunity to thank everyone at USA Rugby for their understanding and support and wish them every success for the future."
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