The first product is to be a fragrance, which will be launched in US department stores in the autumn. It will be backed by a television advertising campaign that will be handled in-house and is likely to feature Spears, although it is unclear whether her songs will feature in the campaign.
In a statement Elizabeth Arden said that Spears was "personally involved" with all aspects of marketing of her upcoming line.
The move by Elizabeth Arden is being seen as an attempt to grab a slice of a younger audience. Its traditional customers are more mature women who buy brands such as Elizabeth Taylor's Passion.
Paul West, president of Elizabeth Arden, said: "She is a talented, fashionable woman who appeals to a young and international consumer base. Together with our department store trade partners, we will introduce a glamorous fragrance concept to the US market in the Fall and we look forward to the launch of the new brand."
Financial terms were undisclosed. The deal was negotiated through Los Angeles licensing company Brand Sense Marketing.
The deal comes as Britney makes something of a return to form with a number one single in the UK with 'Toxic' while her new album 'In the Zone' went to number one in the US, making her the first female artist to have four number one albums in a row. Sales of 'In the Zone' have topped more than 5m CDs.
The news comes just after Elizabeth Arden posted a loss of $11.1m (£6.13m) for the fourth quarter of 2003 due to "restructuring and debt-reduction costs".
Catherine Zeta-Jones signed as Elizabeth Arden's official spokesperson in February 2002 and TV advertising through San Francisco agency Goodby, Silverstein & Partners was unveiled in November 2003.
Britney recently starred in a Pepsi commercial with Pink, Beyonce and Enrique Iglasias in January.
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