Spotify's availability on smartwatches is limited. One of the most popular music services doesn't have the official application dedicated to Apple Watch, nor does it have an application dedicated to Android Wear.
However, Andrew Chang had created app named "Spotty" which in fact is unofficial app made for Apple Watch, and it allows to listen music from Spotify. Spotify contacted Chang some time ago and company forced him to change name of his app, because it sounded too similar to Spotify's name. Few months after it there took place a meeting between Chang and Spotify. This time company contacted to creator of "Spotty" because Spotify decided to coopearate with Chang to create the official application dedicated to Apple Watch.
Yesterday Andrew Chang published an official statement which confirms the collaboration. Formal launch of the app will take place in nearest future.