The first thing you need to do is find the Deep Dark biome underground, usually under mountainous locations. Just remember to be prepared to deal with the Wardens that might appear in this location. The Deep Dark biome will be between coordinates Y=-1 and Y=-64.
After finding the Deep Dark, you will have to find an Ancient City. These only spawn in Deep Dark biomes at Y = -52.
If you are in a higher level of a deep and dark biome, you will have to dig for an ancient city. In these cities there are chests that contain Echo Shards.
That's all you need to know about where to find echo shards in Minecraft and now that we're done, we hope we've been very helpful, so you can find this item without a problem.