Williams was at the streaming platform from 2009 to 2015; the last two-and-a-half years as managing director.
He left Spotify to co-found start-up Words Won’t Do, and was also acting international chief revenue officer at data location marketing company Verve for a year until last July.
Before joining Spotify, Williams spent eight years as head of digital platforms at Global Radio.
He will report to Takumi’s chief executive and co-founder Mats Stigzelius.
Williams said: "When I joined Spotify it had started to shake up the music industry with the shift to streaming. In many ways, influencer marketing has had that same effect among marketers.
"It has come out of nowhere and is now considered by most as an established and effective tactic, especially for brands trying to target millennials. What’s more, we expect to see a lot more growth over the next few years as the millennial market matures."