Ex-England defender and Macclesfield manager Sol Campbell was named boss of League One strugglers Southend United before watching his new side lose 7-1.
Campbell, 45, was in the stands as the Shrimpers fell to their heaviest ever home defeat at the hands of Doncaster.
His first game in charge will be against leaders Ipswich on Saturday.
Former Portsmouth team-mate Hermann Hreidarsson and ex-Manchester United striker Andy Cole will form part of Campbell's coaching team at Roots Hall.
Campbell has signed a deal until the end of the 2021-22 season.
Southend, who were reduced to nine men, still only have one league win this term following the thumping by Doncaster.
They have now conceded 40 goals in 14 matches and remain eight points from safety in 22nd.
It was a sour end to the reign of caretaker manager Gary Waddock, who had been in charge since Kevin Bond left on 6 September.
Ex-Celtic striker Henrik Larsson had looked set to succeed Bond before talks broke down last week.
Campbell played for Arsenal and Tottenham during an illustrious playing career, and kept Macclesfield in League Two last season in his first managerial role before leaving by mutual consent in August.
He was initially interviewed for the vacancy towards the end of last month but Southend chairman Ron Martin made Larsson his first choice before discussions ended.
Former Iceland defender Hreidarsson - who also played for Charlton and Ipswich - will be Campbell's assistant, with ex-England man Cole joining as forwards coach to bring an end to a managerial search which lasted 46 days.
Glenn Speller, BBC Essex sports editor
This news makes more sense than what we were expecting last week, with the untried and unproven Larsson on the verge of joining.
When that move broke down, Ron Martin moved quickly to resurrect talks with Campbell.
He comes with saving Macclesfield on his CV, which will give many Blues fans hope he can repeat that feat.
Campbell is joining a club where morale is fragile and supporter expectations are on the floor. If he can turn this one around, Southend might find themselves fighting off more suitors.