Collinge has spent the past five years at Speed, woking in a number of roles, most recently as associate director. She has led campaigns for clients including Virgin Media, Monitise, Nikon, Imagine Publishing and Interoute.
In her new role she will oversee client services across Clarity’s international client base in the agency's London, Berlin and New York offices.
Collinge said: "Tech start-ups need to be able to scale their comms quickly, so Clarity’s proposition and growing geographic footprint is a perfect blend.
"For me personally, working to grow a PR agency start-up whille launching reputations for the UK’s most innovative tech businesses is a truly exciting prospect and I'm very much looking forward to the challenge."
Sami McCabe, CEO of Clarity PR, said: "To attract someone of Sara's experience and track record is fantastic news for Clarity and our clients."