Drivers will now pay 114.7ppl, the same price as unleaded from tomorrow (Thursday).
It is the first time both fuels have been the same price since 2010.
The price drop follows a continued freeze on fuel duty in today’s budget.
Asda has a national price cap on fuel at all of its 272 filling stations.
Andy Peake, Asda’s senior director for petrol said: “A further freeze on fuel duty is good news for the nation and even better news for our customers. It will allow us to keep offering lower priced fuel with a further 2ppl off diesel in all our petrol stations as of tomorrow.”