I Spy's remit for encompasses home and motor insurance as well as brand.
Nick Jones, managing director of I Spy, said: "Endsleigh's product portfolio, built around the concept of lifelong relationships, fits perfectly into how search works and we are looking forward to delivering some great results for them.
Mike Day, Endsleigh e-commerce manager, said: "I Spy's dedication to detail and the nuances of our brand set them apart from the crowd and we look forward to a productive relationship."
Signet has appointed I Spy to handle paid search for its and high-street chains. The agency won the business from incumbent BigMouth Media following a competitive pitch.
Signet has tasked I Spy with driving traffic to its branded websites for Ernest Jones and H Samuel.
Jones said: "The H Samuel and Ernest Jones brands are ripe for a more integrated paid search platform and we are looking forward to delivering them some strong results."
Nikul Shah, online media manager at Signet, said: "I Spy's understanding of our business imperatives set them apart and I am confident that we will develop a productive relationship with I Spy."
I Spy Search is in its third year and doubled head count to 42 in 2008 after paid and natural search wins for Avon, QVC and Jobsite.