Like Ferguson, the 56-year-old Smith is a Glaswegian and his arrival is expected to take some of the pressure off the United manager, who has been working without an assistant coach since the Portuguese Carlos Queiroz left Old Trafford last summer to take charge of Real Madrid CF.
Smith was Rangers manager from 1991-98, in which time the Ibrox club won seven successive league titles, as well as three league and cup doubles. He subsequently joined Everton FC where he remained for four years until his dismissal in March 2002.
Worked together before
Smith and Ferguson have worked together before, when the former assisted Ferguson in his duties as Scotland manager at the 1986 FIFA World Cup. The pair's association does not end there as Smith's assistant at Goodison Park was Archie Knox, who had previously worked alongside Ferguson at Aberdeen FC and United.
'Talent and background'
Sir Alex said: "I am delighted that Walter has accepted the chance to join United.
There are few people in the game with his experience, knowledge and technical ability. His talent and background will be major assets at such a critical time of the season."
Smith said: "The chance to come to Manchester United is something I couldn't turn down. There are few bigger challenges in football than helping a successful side sustain their achievements. I have huge admiration for what Sir Alex has achieved at United and I'm excited to be part of it."
©UEFA.com 1998-2014. All rights reserved.