Soulmates currently runs in both The Guardian and The Observer newspapers and will have its own site at www.guardian.co.uk/soulmates.
The online service has a search function to allow users to search ads for location, age and gender. It will include dating tips, stories and ideas for putting together a successful ad.
Soulmates advertisers record a phone message, which is screened, transcribed, summarised and then appears in The Guardian, The Observer and on the new site for free.
Respondents can then dial a number to hear the advertiser's voice, at a cost of £1 per minute. Advertisers can choose to receive text messages to notify them when they receive replies to their ad.
Simon Waldman, director of digital publishing at Guardian Newspapers,
said: "Making Soulmates available on Guardian Unlimited, which has a large proportion of users who don't read either paper, will make the service accessible to a whole new audience."
The website will be advertised in The Guardian and The Observer and throughout the Guardian Unlimited network.
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