Barracuda has a brief to drive natural search traffic to the City & Guilds website by optimising its search listings.
It plans to improve the site's rankings with on-page optimisation, new content creation, online PR and inbound link building.
Jumoke Oyadare, digital marketing manager for City & Guilds, said: "We understand that how we harness 'digital' is extremely important in order to continue being recognised as a global benchmark for workplace skills and professional development.
"Finding the right search marketing partner was therefore crucial and our selection procedure had to be thorough."
Barracuda's other clients include IPC Media, the London Stock Exchange and Virgin Media.