Tesco began with a 50 per cent off sale, which is expected to save shoppers a total of £10m. The retailer has also introduced exclusive toys including the relaunch of Hasbro's Action Man.
Asda has responded with another half-price sale (pictured), said to offer £6m in discounts through its Christmas Toy Event. The retailer is also tracking the promotion with a blog by its seasonal toy buyer.
The promotions have been launched in a bid to take a share of the sales in the lead up to the first Christmas since the demise of Woolworths.
A survey of 8,000 people by Asda, which sold almost 7,000 half-price doll houses in one day this week, found that 73 per cent of parents had already kicked off their Christmas shopping and 20 per cent were anxious about the cost of presents for their children.
A spokesperson for the supermarket said: "Shoppers need to be more prepared so they can spread the cost of Christmas, while all retailers will be competing to get customers through their doors."
Meanwhile, Tesco said toy sales have exceeded expectations so far, with the Barbie Musketeer, Tomy Mega Sketcher and remote-controlled cars the best sellers.
A spokesperson for the retailer said: "We started our half-price toy sale at the beginning of October and have already found that many have stocked up early.
"We have more than 100 popular toys at half price or less and expect to save customers over £10m this Christmas."