McDonald's chief executive officer Steve Easterbrook has been fired after violating company policy by engaging in a consensual relationship with an employee.

Key points: Mr Easterbrook said in a company-wide email he agreed with the board that it was time for him to move on

Mr Easterbrook said in a company-wide email he agreed with the board that it was time for him to move on Chris Kempczinski has been named McDonald's new chief executive officer

Chris Kempczinski has been named McDonald's new chief executive officer McDonald's shares more than doubled during Mr Easterbrook's tenure

The board determined that Mr Easterbrook had "demonstrated poor judgment" involving the relationship, McDonald's said in a news release.

Mr Easterbrook relinquished his seat on the company's board as well.

"This was a mistake," Mr Easterbrook said of the relationship in an email to employees on Sunday (local time) released by the company.

"Given the values of the company, I agree with the board that it is time for me to move on."

The departure of Mr Easterbrook, who had led McDonald's since 2015, is among the most significant in corporate America in the past several years over relationships deemed inappropriate.

Scrutiny of executives and their treatment of employees has intensified amid the #MeToo social media movement, which highlighted instances of sexual harassment in the workplace.

In June 2018, Intel Corp chief executive officer Brian Krzanich resigned after an investigation found he had a consensual relationship with an employee that breached company policy.

Chris Kempczinski, most recently president of McDonald's USA, was named the company's new chief executive, effective immediately. He also joined the McDonald's board.

In his own message to employees, Mr Kempczinski thanked Mr Easterbrook for recruiting him to McDonald's and said he expected the company to continue its customer-focused growth plan.

McDonald's chairman Enrique Hernandez Jr called Mr Kempczinski "instrumental" in developing the company's strategic plan.

McDonald's, which recently celebrated the 40th anniversary of its Happy Meal for children, is known for its family-friendly reputation.

McDonald's shares more than doubled during Steve Easterbrook's tenure as the company's CEO. ( AP: Rick Bowmer )

The company did not provide further details on the circumstances surrounding Mr Easterbrook's departure.

McDonald's is expected to disclose financial information related to Mr Easterbrook's dismissal in a securities filing as soon as Monday (local time), the company said.

The company named Joe Erlinger, who has been president of international operated markets, as president of McDonald's USA, succeeding Mr Kempczinski.

Eaterbrook's influence on McDonald's business

McDonald's shares more than doubled during Mr Easterbrook's tenure.

But, in October, the chain missed Wall Street profit estimates for the first time in two years as it spent money remodelling US restaurants and speeding up service to address declining customer visits.

Rival fast food chains in the United States have challenged McDonald's dominance with value meals and new menu items, including plant-based burgers and meat substitutes launched by rivals including restaurant brands Burger King and KFC.

The remodelling of the company's 14,000 US restaurants included introducing digital ordering kiosks and mobile ordering as well as pay-and-pickup services, while partnering with app-based delivery services GrubHub, Uber Eats and DoorDash.

The world is different than it was in 1955, Mr Easterbrook said during an October call with investors.

Mr Easterbrook turned around McDonald's operations in the UK, where he was born, by refocusing on burgers and burnishing the brand with an ad campaign that sought to debunk unflattering rumours about its food.

Reuters/AP