diff --git a/Doxygen b/Doxygen
index a61d3f11b..22e3d69ad 100644
--- a/Doxygen
+++ b/Doxygen
@@ -38,7 +38,7 @@ PROJECT_NAME           = "ESPHome"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 2021.9.0
+PROJECT_NUMBER         = 2021.9.1
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/Makefile b/Makefile
index a0d4508e9..c9d82a149 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 ESPHOME_PATH = ../esphome
-ESPHOME_REF = 2021.9.0
+ESPHOME_REF = 2021.9.1
 
 .PHONY: html html-strict cleanhtml deploy help webserver Makefile netlify netlify-api api netlify-dependencies svg2png copy-svg2png
 
diff --git a/_static/version b/_static/version
index 085473d65..fe2da35aa 100644
--- a/_static/version
+++ b/_static/version
@@ -1 +1 @@
-2021.9.0
\ No newline at end of file
+2021.9.1
\ No newline at end of file
diff --git a/changelog/2021.9.0.rst b/changelog/2021.9.0.rst
index 8ec36ed26..795a07bf3 100644
--- a/changelog/2021.9.0.rst
+++ b/changelog/2021.9.0.rst
@@ -56,6 +56,15 @@ The template selects, numbers and switches now have more validations on them pre
 If you do not set a ``lambda`` then you are required to make them either ``optimistic: true``, or
 utilise the ``set_action`` (select/number) / ``turn_on_trigger`` (switch).
 
+Release 2021.9.1 - September 20
+-------------------------------
+
+- Fix MQTT discovery for sensor state_class :esphomepr:`2331` by :ghuser:`paulmonigatti`
+- Light transition fixes :esphomepr:`2320` by :ghuser:`oxan`
+- Cease using deprecated Cover methods in automations :esphomepr:`2326` by :ghuser:`oxan`
+- Apply color brightness to addressable light effects :esphomepr:`2321` by :ghuser:`oxan`
+- Add readv and writev for more efficient API packets :esphomepr:`2342` by :ghuser:`OttoWinter`
+- Clean-up sensor integration :esphomepr:`2275` by :ghuser:`oxan`
 
 Full list of changes
 --------------------
diff --git a/conf.py b/conf.py
index 2fdbda59d..06dd9df64 100644
--- a/conf.py
+++ b/conf.py
@@ -69,7 +69,7 @@ author = "Otto Winter"
 # The short X.Y version.
 version = "2021.9"
 # The full version, including alpha/beta/rc tags.
-release = "2021.9.0"
+release = "2021.9.1"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/guides/supporters.rst b/guides/supporters.rst
index 88745d69b..e6097ed2e 100644
--- a/guides/supporters.rst
+++ b/guides/supporters.rst
@@ -236,6 +236,7 @@ Contributors
 - `Fritz Mueller (@fritzm) <https://github.com/fritzm>`__
 - `Marc Egli (@frog32) <https://github.com/frog32>`__
 - `mr G1K (@G1K) <https://github.com/G1K>`__
+- `Aljaž Srebrnič (@g5pw) <https://github.com/g5pw>`__
 - `Gabe Cook (@gabe565) <https://github.com/gabe565>`__
 - `Gareth Cooper (@gaco79) <https://github.com/gaco79>`__
 - `galagaking (@galagaking) <https://github.com/galagaking>`__
@@ -374,6 +375,7 @@ Contributors
 - `larsonmpdx (@larsonmpdx) <https://github.com/larsonmpdx>`__
 - `lein1013 (@lein1013) <https://github.com/lein1013>`__
 - `Riku Lindblad (@lepinkainen) <https://github.com/lepinkainen>`__
+- `Luca Gugelmann (@lgugelmann) <https://github.com/lgugelmann>`__
 - `Juraj Liso (@LiJu09) <https://github.com/LiJu09>`__
 - `Lazar Obradovic (@lobradov) <https://github.com/lobradov>`__
 - `Barry Loong (@loongyh) <https://github.com/loongyh>`__
@@ -713,4 +715,4 @@ Contributors
 - `ZTX18 (@ZTX18) <https://github.com/ZTX18>`__
 - `Christian Zufferey (@zuzu59) <https://github.com/zuzu59>`__
 
-*This page was last updated September 16, 2021.*
+*This page was last updated September 20, 2021.*