The system, which is being dubbed "HyperTargeting" by the News Corporation-owned MySpace, will face competition from this week when it rolls out its own targeted ad system.
said that HyperTargeted ads would allow it to generate greater click-through response rates for advertisers, by placing ads on the profiles of users chosen on the basis of their interests, tastes and likes.
It is understood that MySpace has signed up more than 50 advertisers to HyperTargeting, including Procter & Gamble, Microsoft and Ford.
Fox Interactive Media, the parent company of MySpace, said the ads system is "not keyword based", and that advertisers would be able to identify a particular interest irrespective of whether they have mentioned it before.
Adam Bain, vice-president of product and technology at Fox Interactive Media, said that the system was looking at what MySpace users say in their profiles and what they do online.
He said: "It's not keyword based, so they don't have to mention Tom Cruise for us to know they're a fan; we're smart enough to understand the movies they list have Tom Cruise in them.
"The thing we heard from them is they wanted advertisements to be more contextually relevant to them. If they have to live with ads, they want an ad to be engaging."
Meanwhile, Facebook is set to make major changes to its own online ad service system tomorrow. These are believed to centre on increasing the click-through rate for ads -- the benchmark that advertisers traditionally measure an ad's success rate from.
MySpace plans to increase the amount of services available to brands on HyperTargeting, including a segmentation process spanning up to 100 different categories. This would allow advertisers to gain a greater understanding of which consumers they should be targeting online.
Fox Interactive Media said MySpace users would be able to opt-out of receiving targeted ads, allowing them to have some control over which brands advertised on their homepage.