The retailer said it was implementing “social distancing controls” including two-metre spacing and limits on the number of goods customers can buy.
However some critics on social media have panned the decision, calling for the gradual lifting of lockdown measures, after long queues were seen at stores in London, Bristol, Kent and in the Wirral .
B&Q shut all of its stores at the end of March but following a trial last weekend, opened shops across the UK under a graduated scheme.
A spokesman for the store previously told the Standard it is following “best practice” and operating outlets with “social distancing measures in place”.
Photos depicting long lines of customers waiting to enter shops under the hot sun have surfaced online.
Taking to social media, one Twitter user said: “Hardly a surprise. Hordes of people descending onto B&Q was always going to happen when they reopened.
“Other countries’ Government’s have eased them out of lockdown, the UK has been eased out by B&Q and a bunch of selfish idiots who are risking undoing most peoples good work.”
Another added: “Unlocking the lockdown … by the backdoor. I missed this. Why are B&Q opening stores to the general public?
“Understandable for essential service personnel to be able to use them atm, but for the rest of us? Once one starts, they’ll all follow suit.”
One user said: “Went past my local B&Q today. Car park rammed full. #lockdown is going to fully collapse within a couple of weeks if Boris Johnson & co don’t get a grip.”
One person claimed the lockdown will last longer now that the stores have reopened.
“I would just like to say well done to B&Q & Homebase for opening up at the peak of the virus,” he said.
“We will be in lockdown for longer due to greed and not people’s safety.”
Another posted that the situation was “absolute carnage” and said: “With B&Q opening all their stores they have single handedly ended lockdown. Roads are now busier and just been to Morrison’s it’s absolute carnage”.
However some users said the retailer was left with no choice.
“The fact is, B&Q (like many businesses) were not told to close, they chose too.
“While competitors like Wickes adapted they did not, and have not choice but to reopen or crash. It seems worse now because they were closed all this time.”
A B&Q spokesperson said: “As an essential retailer, we’re committed to providing the best possible service to support customers’ home improvement needs at this difficult time, while keeping customers and colleagues safe.
“Having watched other essential retailers support social distancing in their stores, we are now following their best practice and are reopening some stores with strict social distancing measures in place.”