The aggregator compares prices from 1,500 labels on more than 40 sites, including well known retailers such as ASOS, House of Fraser and TopShop. It also has an ethical slant and pushes eco-friendly brands.
The site will compete with eBay's fashion store, which launched in April and hosts many of the same brands, and Facebook stores, including sites for French Connection and ASOS. Stylecompare also plans to eventually roll-out a Facebook store.
To promote the launch, StyleCompare.co.uk is recruiting a panel of judges to spot and promote rising fashion stars.
The social media campaign is backed-up with search and email spend. The company also aims to develop a PR strategy with notable fashion bloggers.
Jonny Challenger, co-founder of StyleCompare.co.uk said: "StyleCompare.co.uk brings together thousands of products, brands and retailers onto one site – making it easier and quicker to shop online. We know shoppers like choice.
"So we've given them that and at the same time segmented our data to make it easier to shop based on individual style and budget. Visitors can personalise their shopping experience by searching for items by specific price (not broad brackets), new-in items, product, label and retailer."
New signings this month will include New Look, streetwear outfit Superdry, multi-channel leader John Lewis and luxury retailer Net-a-Porter.
Challenger said: "Fashion comparison on this scale is still in its infancy in the UK but we predict that it will really take off this year. As customer's tastes develop and become more sophisticated it is important that as an online shopping site we react and offer them a service that truly meets their needs."
The site aims to have a million monthly users by the end of 2011.