The 69-year-old has been "required to relinquish his duties" at the British automotive firm, he confirmed in a statement released late Tuesday and shared widely on social media
"Ultimately it has become clear to me through this process that neither TAG nor Mumtalakat (McLaren's other major shareholders) share my vision for McLaren and its true growth potential," Dennis said.
McLaren had confirmed earlier Tuesday
that the group's longtime CEO and chairman had been put on gardening leave, though he remains a shareholder and director in the company.
Dennis has been a key figure at the top of McLaren and its F1 team for 35 years, although his statement and subsequent media reports suggest one of the reasons given for his removal was his style of management.
"The grounds they have stated are entirely spurious; my management style is the same as it has always been and is one that has enabled McLaren to become an automotive and technology group that has won 20 Formula One world championships and grown into an £850 million a year business," he said.
"Throughout that time I have worked closely with a series of talented colleagues to keep McLaren at the cutting edge of technology, to whom I will always be extremely grateful.
Reports over the weekend
suggested Dennis had failed in a court bid to prevent his removal after he had sought to bring in investors to back him in gaining full control of the company.
Dennis said he will still seek to pursue new opportunities while maintaining his interest in McLaren as a shareholder. Bahrain's Mumtalakat Holding Company reportedly has a 50% stake, while Mansour Ojjeh's TAG Group and Dennis own 25% each.
"I will continue to use my significant shareholding in both companies and my seats on both boards to protect the interests and value of McLaren and help shape its future," he added.
"In addition I intend to launch a new technology investment fund once my contractual commitments with McLaren expire.
"This will capitalize on my expertise, my financial resources, together with external investment to pursue the many commercial opportunities I have been altered in recent years but have been unable to take up while being so committed to the existing business."
McLaren had won three world titles when Dennis arrived in 1980, the last coming four years earlier when James Hunt edged a classic battle with Niki Lauda.
The British team collected 13 drivers' and constructors' crowns between 1984-1991 and then did another double in 1998.
It had to wait until 2008 for its next driver title as Lewis Hamilton claimed his first, and since his departure to Mercedes it has struggled to compete despite signing former world champions Fernando Alonso and Jenson Button.
Dennis stood down as team boss in early 2009 but returned to replace his successor Martin Whitmarsh in 2014.
In the first year of its reunion with Honda
, the engine manufacturer with whom it had so much success, McLaren finished ninth in 2015 with its worst points tally since 1980.
This season, McLaren is sixth in the standings ahead of the final race in Abu Dhabi on November 27.