The campaign, which uses the strapline 'Start networking not just Linkin', focuses on the business-building benefits of active professional networking.
During the next month nearly 400 XING billboards will be on display in some of London's busiest underground stations including Oxford Circus, Victoria, Waterloo, Bank and Canary Wharf, and it will run ads in freesheet Metro.
XING has also launched an online marketing campaign; its ads will feature on websites including Guardian.co.uk, Timesonline.co.uk, Sky News and Reuters, targeting a predominantly male audience.
XING has more than 6m active members worldwide including more than 500,000 paying subscribers. Its main markets in Europe include Germany, where it has a strong presence.
During the campaign, the company is launching a promotion for members in the UK and Ireland. Any XING member who invites a friend from the UK or Ireland to sign up will receive one free month of Premium Membership, which allows full access to all the site's services. The promotion runs until 31 October.