Long, 36, has spent the past 18 months as assistant coach at Salford before resigning last week. He will now join his hometown club, for whom he made 12 appearances back in the 1990s.
He said: “This is a really exciting time for me in my career and I am looking forward to joining the Wigan Coaching Staff and demonstrating my commitment to the Wigan standards and discipline. This is a real opportunity for me to develop my own skills in a new coaching role and learn off the Club’s very experienced Backroom Staff.
“I feel I have a lot to offer the Club from my time as a player and assistant coach and can’t wait to get learning.”
Long, who left Wigan for Widnes in 1997, spent much of his playing career with the Warriors’ arch-rivals St Helens.
He earned 21 caps in total for England and Great Britain, and hung up his boots in 2011 following two seasons at Hull.
Wigan Rugby Manager, Kris Radlinski, said: “Sean is without doubt a quality young coach of potential who knows the game of rugby league inside and out.
“Our senior coaching staff will integrate him into our system, teach him the Wigan style of discipline, control and hard work and also tap into his vast pool of playing experience. The fact that he is a ‘hands-on coach’ who can step in and show how it should be done, really appeals to us.
“This appointment really highlights what our Club philosophy is all about over the coming years. It is important that we have strong succession plans in place for both players and the development of our staff.”