The era of advertising Sorrell ushered in has been about scale as a handful of big players - WPP, France's Publicis and Havas, Japan's Dentsu and New York-based Interpublic and Omnicom - have hoovered up smaller agencies.
His resignation will be one of the most significant exits of a FTSE-100 chief executive for many years.
"It wasn't a boardroom battle but the way they behaved in his eyes, the manner they handled the investigation, in the end he thought I'm 73-years old I don't need this s**t", one person close to the process said.
Roberto Quarta, the company's chairman, will now lead the organization in the interim. He denied the allegations but in a letter to WPP staff published late on Saturday he said the "current disruption" was "putting too much unnecessary pressure on the business".
Sorrell, who will continue to be available to the board with his valued guidance signed off saying, "As a Founder, I can say that WPP is not just a matter of life or death, it was, is and will be more important than that".
The company has also named Mark Read, who runs WPP's digital operation Wunderman, and its European chief operating officer Andrew Scott as joint chief operating officers.
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WPP said the investigation, which regarded financial impropriety, had concluded.
As the architect of the global empire which began in the humble form of the cash shell Wire and Plastic Products, Sir Martin has amassed rich rewards from his success.
Sorrell, who founded the British ad giant and has been at the helm for the past 33 years, stepped down less than a fortnight after the group launched an independent investigation into the allegations.
However, his departure will leave the company he built virtually from scratch facing profound questions about its future direction.
WPP's biggest clients globally include the likes of Ford, Procter & Gamble and Unilever, which it services through traditional advertising agency networks such as Ogilvy, J Walter Thompson and Grey.
That has left WPP and its peers - the French group Publicis and Interpublic of the USA - being buffeted by headwinds which also include the disintermediation of digital platforms such as Facebook. JP Morgan maintained the shares of WPP in report on Tuesday, November 21 with "Overweight" rating.