Lambert, who was in charge of Ipswich's East Anglia rival Norwich City between 2009 and 2012, replaces Paul Hurst, who was dismissed last week after a 2-0 defeat at leader Leeds United a day earlier.

Ipswich is four points adrift of safety having won only one league game and the club has turned to 49-year-old Lambert to turn its fortunes around.

The former Scotland international, who left his role as Stoke City boss in May after their relegation from the Premier League, has signed a deal at Portman Road until 2021.

Lambert, who watch Ipswich lose again from the stands at Millwall, told the club's official website: "I can't wait to get going and I'll be using all my experience.

"I know about the history of the club, what a fantastic football club it is and I'm proud to be the manager here."