diff --git a/Doxygen b/Doxygen
index 2c9389253..7149a5681 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         = 2021.9.0b3
+PROJECT_NUMBER         = 2021.9.0b4
 
 # 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 1b8965fc2..624fd343e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 ESPHOME_PATH = ../esphome
-ESPHOME_REF = 2021.9.0b3
+ESPHOME_REF = 2021.9.0b4
 
 .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 10cc8a5e9..49218f589 100644
--- a/_static/version
+++ b/_static/version
@@ -1 +1 @@
-2021.9.0b3
\ No newline at end of file
+2021.9.0b4
\ No newline at end of file
diff --git a/conf.py b/conf.py
index 7e7bc9347..f2dd4aec1 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 = "2021.9.0b3"
+release = "2021.9.0b4"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.