Burger King is removing all plastic toys from its children's meals served in the UK from Thursday, to save an estimated 320 tonnes of waste annually.
In a separate announcement coinciding with its rival, McDonald's said it will give customers the option of swapping plastic toys in its Happy Meals for fruit bags or books.
It will begin the option of the fruit bag next month followed by the book from early next year.
Burger King said the move was part of a wider commitment to reduce its use of plastic, and admitted it was "spurred on" by Southampton sisters Ella and Caitlin McEwan's petition against the use of plastic toys in children's meals.
The Change.org petition, calling on Burger King and McDonald's to "think of the environment and stop giving plastic toys with their kids' meals", has attracted half a million signatures.
Burger King UK chief executive Alasdair Murdoch said: "We're making a start. This is a step in the right direction.
"If it makes other competitors move their practices forward, that can only be a good thing."
The announcements follow increasing consumer pressure on fast food chains to stop handing out the single-use plastic toys, which parents commonly complain are promptly discarded and only contribute to the waste crisis.
McDonald's said swapping out the toys, alongside its roll-out of paper straws in restaurants, the removal of McFlurry plastic lids and the removal of single-use plastic from McDonald's salads, would reduce waste by 1,005 metric tonnes annually.
McDonald's UK and Ireland chief executive Paul Pomroy said: "We recognise that some people may not want a plastic Happy Meal toy, but we also know that the gifts provide fun for many families and children.
"That's why we'll be running these trials, in order to give our customers a choice; they also can choose not to have a toy or gift at all.
"It's important we understand what our customers want and we'll learn a lot from whether they choose a fruit bag or a book over a toy.
"At the same time, we will be evolving what the toy or gift is - new authors as part of Happy Readers, paper-based toys and board games."We
know that our Happy Meal is much loved by our customers so any changes need to be carefully considered."
Burger King is installing amnesty bins in every one of its restaurants across the UK, where people can drop off any free plastic meal toys, including those given away with confectionery or within children's magazines.
The plastic will be transformed into new play areas and restaurant items, including interactive trays.
Fernando Machado, global chief marketing officer at Burger King, said: "We are a global brand, and the UK market will be leading the way in making this first step towards change, which is part of our wider commitment on reducing plastics.
"Work is currently under way across all of our markets to look at how we can completely move away from non-biodegradable plastic toys by 2025."