Ergatoudis managed Radio 1's music output for 10 years, and was a key figure at the radio station. He previously worked as the head of music policy for the BBC's hip hop and grime radio station 1Xtra.
The departure of Ergatoudis to a technology company follows the so-called "Apple crumble" that took place earlier this year.
Radio 1 DJ Zane Lowe left the BBC for Apple, where he became a host on the new Beats 1 online radio station. He was followed by at least four other BBC staff members to Apple.
Ergatoudis said in a statement: "I am leaving BBC Radio 1, the world's greatest music radio station, to join the world's leading digital music service and I couldn't be more excited. There are huge opportunities ahead for Spotify and I am delighted to be joining their brilliant team. My passion for music has driven my entire career and this next step is like a dream come true."
And Spotify's global head of content programming Nick Holmstén said "George is one of the most well known and well respected figures in the British music industry, and we are enormously proud and excited to have him join us at Spotify. His gifts for music curation and identifying exciting new talent are second to none, and I can think of no one better to help Spotify introduce music fans to a wealth of new music and a new generation of artists that they are going to love."