Following this period, the Red Devils and the 63-year-old have agreed that the German will continue in a consultancy role for a further two years.
John Murtough, Manchester United football director, said: "Ralf is one of the most respected coaches and innovators in European football.
"He was our number one candidate for interim manager, reflecting the invaluable leadership and technical skills he will bring from almost four decades of experience in management and coaching.
"Everyone at the club is looking forward to working with him during the season ahead, and then for a further two years in his advisory role."
Rangnick, who studied at the University of Sussex and made several appearances for Southwick back in the 1979-80 season, said: "I am excited to be joining Manchester United and focused on making this a successful season for the club.
"The squad is full of talent and has a great balance of youth and experience. All my efforts for the next six months will be on helping these players fulfil their potential, both individually and, most importantly, as a team.
"Beyond that, I look forward to supporting the club’s longer-term goals on a consultancy basis."