The next-day service has been developed to replicate the speed of similar services used by the building trade and is available at nextday.diy.com. Delivery is free on orders of over £50.
Additions to the site include a "voice of the customer" section, where users can give feedback and post suggestions on improving services. B&Q is also planning to introduce a product ratings and review service next month.
During the first first week of its relaunch, DIY.com has attracted over 1.2m visits, according to the retailer, while nextday.diy.com has attracted over 250,000 visits.
Jonathan Brown, B&Q's director of multi-channel, said: "The new site is designed to give our customers all the tools and confidence they need to tackle home improvement projects themselves with the added benefit of next day delivery."
This week, B&Q owner Kingfisher said that profits for the UK arm of B&Q fell 19% to £106m and sales were down 6.1% in the year to the end of January.
While its kitchen and bathroom ranges were hit particularly hard, with a drop in sales of 8%, DIY sales proved more resilient and dropped just 3%.