The website stocks the company's Reserve portfolio, which includes Johnnie Walker Blue Label, Johnnie Walker Gold Label Reserve, Tanqueray No. Ten, Ciroc vodka, Ketel One vodka and selected Diageo single malts.
The new site marks the first time Diageo will sell directly to people online in the UK.
Philippa Dickson, managing director of Alexander & James said: "We created Alexander & James in response to the way people are seeking to purchase luxury items online. We identified an opportunity to create a luxury e-commerce platform that would be engaging and inspiring, bringing the brand product credentials to life – craftsmanship, heritage, provenance."
Diageo partnered with digital agency Huge to create and design the Alexander & James brand. Huge has also designed "premium packaging" for Alexander and James purchases.
Alexander & James will deliver to their customers within 2-3 days in the UK. The site features, among other things, the ability to store and send to multiple addresses from one purchase and will be integrated with Facebook to enable members to share wish lists and get reminders of friends birthdays.