BBC Two has announced that the show will return in the autumn for a new run of seven 30-minute episodes in the autumn.
The new series promises to feature "Government embarrassment, ministerial cock-ups, Coalition rows, backroom deals, policy U-turns, spin-doctoring, political back-stabbing, wild media speculation, and more time spent with one's family".
Teasing the fourth series, Iannucci said: "This series takes The Thick of It into exciting and uncharted territory: a new Coalition Government, and Malcolm and Nicola fretting in the wings.
"For the first time too a storyline takes us all the way through the series right to the bitter, bitter end, with Government and Opposition convulsed in an incident that questions every political convention imaginable, but in a funny way."
Roger Allam is back as Peter Mannion MP, the new Secretary of State for The Department of Social Affairs and Citizenship (DOSAC), supported by a team of special advisors.
Number 10's Director of Communications Stewart Pearson is played by Vincent Franklin, while Geoffrey Streatfeild is cast as new Coalition partner, DOSAC's Junior Minister Fergus Williams MP.
Rebecca Front and Peter Capaldi reprise their roles as Nicola Murray MP and foul-mouthed spin doctor Malcolm Tucker, who are still desperately hoping for a return to power after being relegated to Her Majesty's Loyal Opposition.
Chris Addison, Joanna Scanlan, James Smith, Olivia Poulet, Will Smith, Ben Willbond and Rebecca Gethings complete the ensemble cast.
BBC Two Controller Janice Hadlow said: "I am delighted to welcome The Thick Of It back to BBC Two. It is an essential part of the BBC Two comedy offering this year. A new Coalition government, what better time for a new series of The Thick Of It?"
Mark Freeland, Head of Comedy at the BBC, said: "I'm excited to see The Thick Of It return to our screens. With an outstanding cast and team, it is still at the bleeding edge of British politics, one of the freshest and most biting satires you'll find on TV.
"No other show could coin the term 'Omnishambles' and see it become part of the political lexicon."
