Sanders, who was previously head of search and performance media at comms planning and buying agency Rocket, will report to another media agency alumnus Toby Gunton, who was appointed as Edelman UK general manager, digital in September last year.
Prior to joining Rocket, Sanders was deputy head of search at Omnicom-owned PHD Media. According to his LinkedIn profile, he has worked for clients including Sega, Porsche and Southwest Trains.
Gunton said: "Tristan is bringing an incredibly in-depth knowledge of paid digital channels and has strong relationships with the media owners and technology providers we are increasingly working with."
As part of the newly created role Sanders will be responsible for what the agency described as its "growing" paid media offering, which includes social, search and partnerships.
He said: "Amplifying content in social media is becoming an ever more important skill. Edelman realises this and want to be at the forefront of understanding these audiences."