Campbell hired as Southend boss
Campbell is back in management after quitting as Macclesfield boss in the close-season.
The ex-England international signed a two and a half year deal with Southend, who are second from bottom of League One with just one win from 13 games.
Campbell kept Macclesfield up against the odds in his first managerial role, having taken over last November with the side five points from safety, but he faces arguably an even tougher task at the Shrimpers.
Southend are already eight points from safety, with only crisis club Bolton keeping them off the foot of the table, and have taken just one point from their last four games.
He will take over from caretaker Gary Waddock following Tuesday's home game with Doncaster.
His first match in charge will be at home to leaders Ipswich on Saturday.
Campbell will be assisted by former Icelandic international Hermann Hreidarsson, while former Manchester United striker Andy Cole has been named as his forward and attack coach.