The agency will handle all aspects of PR activity, including media relations and integrated digital PR, starting September 2009.
Speed won the account following a four-way competitive pitch. Bite was the incumbent on the account before it was put out to pitch late last year.
Speed has been tasked with maintaining and reinforcing Symantec's leadership in security as well as promoting the company's wider portfolio of solutions in storage and data management.
Symantec UK & Ireland PR manager Abigail Lovell said: ‘Symantec is the third largest independent software company in the world so we wanted a PR consultancy that could provide us with strong strategic counsel and enable us to move our traditional and social media engagement to the next level.'
Gerry Grewal, joint head of Speed's technology practice and leader of the pitch team will head up the account.
Edelman won Symantec's consumer activity in January.