The new-look site incorporates HMV's new brand identity and "Get Closer" strapline, and provides online shoppers with enhanced usability.
Justin Moodie, HMV's head of online, said: "After months of usability research, design and coding we've completely changed the look and feel of the HMV site -- it's more open, bright and welcoming.
"We've changed our messaging to make it easier for customers to find what they want and then buy it; standardised our icons to make the site more intuitive; and updated all our promotions and offers to reflect the new look of the company.
HMV has also redesigned its customer bulletins to be easier to use, more interesting to read and better targeted to what customers want. More changes are planned in the coming months, including the introduction of a ratings and reviews system, customer tagging, a new wish-list, an improved shopping basket and checkout.
Other changes will include improvements to navigation and the integration of the digital and physical product offering. This will encompass a new in-store kiosk, with free downloadable music and movies.
Moodie said: "Since the rebrand, just weeks ago, we've experienced our highest-ever margin rates, average transaction values, email open rates and email sales."
Code has worked with HMV UK since 2002, and has been the brand's retained digital design agency since 2006, providing ongoing creative campaign support, site design and development. Since its launch, HMV's UK site has won numerous industry awards, including best online retailer in last year's Fresh Awards.