Craig Newmark, the website's founder, wrote of the expansion two days ago, saying that the site now covers 570 cities.
The new UK additions include Bath, Coventry, Derby, Dundee, Essex, Kent and Nottingham.
, which launched in San Francisco in 1995, contains jobs, housing, goods, services, local activities and advice. It does not charge individuals to advertise, as a paper might, nor does it take a cut of sales in the manner of eBay. Similarly, it does not carry ads.
Instead, the site obtains its revenue from charging businesses in US cities to place job ads.
Craigslist receives more than 9bn page views per month and its users self-publish more than 30m new classified ads each month, according to the site.