, which can be accessed from any mobile internet device, allows consumers to read the top 10 online news, sport, Bizarre and Sun Woman stories, as well as daily Mystic Meg horoscopes.
There is no charge or subscription fee for accessing the site, but network data charges will apply.
After reading the first story without logging in, readers are asked to opt into The Sun's marketing database beyond that point.
Other content available for download includes "Page 3" wallpapers and videos, ringtones and other video content such as The Sun virals, which incur a charge of between 25p and £3, depending on the content.
Users can also sign up to receive alert services including news, sports, Bizarre, football, Mystic Meg, lottery results and racing tips.
All text alert services are 25p per text with the exception of 'Love Match', which is 50p and racing tips which are £1 per text.
Andrew Bagguley, head of mobile strategy at News Group Newspapers, said: "There are more than 8m consumers of mobile news and information services in the UK in any given month, and The Sun is keen to get a head start in extending its brand into the mobile space and reaching new audiences.
"The flexibility and ease-of-use of the .mobi domain and open standards has enabled us to create content which is just as exciting and usable on a mobile as it is on a PC."
David Ryder, dotMobi's chief marketing officer, said: "TheSun.mobi creates a strong brand presence for The Sun in the mobile environment and enables the paper to launch exciting cross-channel marketing initiatives and extend partnerships and product offerings with advertisers."
Readers can either type "TheSun.mobi" into their phone's browser to access the site, or text 'Sun' to 85080 to receive a link to the site.
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