diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5cbcc6089..887e20f66 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Remove deprecated GDAL/GEOS/PROJ support (#1113).
 - Remove vendored `jq` binary (#1112).
 - Remove redundant Mercurial install step (#1111).
 - Remove support for the Cedar-14 stack (#1110).
diff --git a/Makefile b/Makefile
index 84668a7a9..185fc2fa0 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,7 @@ STACK_IMAGE_TAG := heroku/$(subst -,:,$(STACK))-build
 
 check:
 	@shellcheck -x bin/compile bin/detect bin/release bin/test-compile bin/utils bin/warnings bin/default_pythons
-	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/gdal bin/steps/geo-libs bin/steps/nltk bin/steps/pip-install bin/steps/pip-uninstall bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/python
+	@shellcheck -x bin/steps/collectstatic bin/steps/eggpath-fix  bin/steps/eggpath-fix2 bin/steps/nltk bin/steps/pip-install bin/steps/pip-uninstall bin/steps/pipenv bin/steps/pipenv-python-version bin/steps/python
 	@shellcheck -x bin/steps/hooks/*
 
 test:
diff --git a/bin/compile b/bin/compile
index 150dc83bc..6d48b4ddc 100755
--- a/bin/compile
+++ b/bin/compile
@@ -50,8 +50,6 @@ fi
 # environment variable mechanism (the ENV_DIR).
 S3_BASE_URL="${BUILDPACK_S3_BASE_URL:-"https://heroku-buildpack-python.s3.amazonaws.com"}"
 # This has to be exported since it's used by the geo-libs step which is run in a subshell.
-# TODO: Stop exporting once the geo-libs step is removed or no longer uses `sub_env`.
-export S3_BASE_URL
 
 # Default Python Versions
 # shellcheck source=bin/default_pythons
@@ -137,6 +135,7 @@ export LANG=en_US.UTF-8
 # `~/.heroku/vendor` is an place where the buildpack may stick pre-build binaries for known
 # C dependencies. This section configures Python (GCC, more specifically)
 # and pip to automatically include these paths when building binaries.
+# TODO: Stop adding .heroku/vendor here now that the buildpack no longer vendors anything.
 export C_INCLUDE_PATH=/app/.heroku/vendor/include:/app/.heroku/python/include:$C_INCLUDE_PATH
 export CPLUS_INCLUDE_PATH=/app/.heroku/vendor/include:/app/.heroku/python/include:$CPLUS_INCLUDE_PATH
 export LIBRARY_PATH=/app/.heroku/vendor/lib:/app/.heroku/python/lib:$LIBRARY_PATH
@@ -176,8 +175,6 @@ cp -R "$CACHE_DIR/.heroku/python-stack" .heroku/ &> /dev/null || true
 cp -R "$CACHE_DIR/.heroku/python-version" .heroku/ &> /dev/null || true
 # A plain text file which contains the current sqlite3 version being used (used for cache busting).
 cp -R "$CACHE_DIR/.heroku/python-sqlite3-version" .heroku/ &> /dev/null || true
-# Any pre-compiled binaries, provided by the buildpack.
-cp -R "$CACHE_DIR/.heroku/vendor" .heroku/ &> /dev/null || true
 # "editable" installations of code repositories, via pip or pipenv.
 if [[ -d "$CACHE_DIR/.heroku/src" ]]; then
   cp -R "$CACHE_DIR/.heroku/src" .heroku/ &> /dev/null || true
@@ -263,16 +260,6 @@ fi
 # shellcheck source=bin/steps/eggpath-fix
 source "$BIN_DIR/steps/eggpath-fix"
 
-# Support for Geo libraries. This is deprecated functionality.
-# It is undocumented.
-# shellcheck source=bin/steps/geo-libs
-sub_env "$BIN_DIR/steps/geo-libs"
-
-# GDAL support.
-# This is part of the Geo support.
-# shellcheck source=bin/steps/gdal
-source "$BIN_DIR/steps/gdal"
-
 # SQLite3 support.
 # This sets up and installs sqlite3 dev headers and the sqlite3 binary but not the
 # libsqlite3-0 library since that exists on the stack image.
@@ -370,7 +357,6 @@ mkdir -p "$CACHE_DIR/.heroku"
 cp -R .heroku/python "$CACHE_DIR/.heroku/"
 cp -R .heroku/python-version "$CACHE_DIR/.heroku/"
 cp -R .heroku/python-stack "$CACHE_DIR/.heroku/" &> /dev/null || true
-cp -R .heroku/vendor "$CACHE_DIR/.heroku/" &> /dev/null || true
 if [[ -d .heroku/src ]]; then
   cp -R .heroku/src "$CACHE_DIR/.heroku/" &> /dev/null || true
 fi
diff --git a/bin/steps/gdal b/bin/steps/gdal
deleted file mode 100755
index 6b0fa6fae..000000000
--- a/bin/steps/gdal
+++ /dev/null
@@ -1,41 +0,0 @@
-#!/usr/bin/env bash
-
-# This script serves as the GDAL build step of the
-# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
-# compiler.
-#
-# A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
-# adapter between a Python application and Heroku's runtime.
-#
-# This script is invoked by [`bin/compile`](/).
-
-# The location of the pre-compiled cryptography binary.
-VENDORED_GDAL="${S3_BASE_URL}/${STACK}/libraries/vendor/gdal.tar.gz"
-
-PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
-
-# Syntax sugar.
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-
-# If GDAL exists within requirements, use vendored gdal.
-if (pip-grep -s requirements.txt GDAL gdal pygdal &> /dev/null) then
-
-  if [[ ! -f ".heroku/vendor/bin/gdalserver" && "${STACK}" == 'heroku-20' ]]; then
-    puts-warn "The buildpack's built-in GDAL functonality is not supported on Heroku-20."
-    puts-warn "Please use this buildpack instead: https://github.com/heroku/heroku-geo-buildpack"
-
-  elif [[ ! -f ".heroku/vendor/bin/gdalserver" ]]; then
-    puts-warn "The vendored GDAL package in the Heroku Python Buildpack now deprecated."
-    puts-warn "To enable GDAL use an alternative buildpack is available here - https://github.com/heroku/heroku-geo-buildpack"
-
-    echo "-----> Noticed GDAL. Bootstrapping gdal."
-    mkdir -p .heroku/vendor
-    # Download and extract cryptography into target vendor directory.
-    curl "$VENDORED_GDAL" -s | tar zxv -C .heroku/vendor &> /dev/null
-    mcount "steps.vendor.gdal"
-  fi
-
-  GDAL=$(pwd)/vendor
-  export GDAL
-fi
diff --git a/bin/steps/geo-libs b/bin/steps/geo-libs
deleted file mode 100755
index 2e3a85ad6..000000000
--- a/bin/steps/geo-libs
+++ /dev/null
@@ -1,58 +0,0 @@
-#!/usr/bin/env bash
-
-# This script serves as the GDAL build step of the
-# [**Python Buildpack**](https://github.com/heroku/heroku-buildpack-python)
-# compiler.
-#
-# A [buildpack](https://devcenter.heroku.com/articles/buildpacks) is an
-# adapter between a Python application and Heroku's runtime.
-#
-# This script is invoked by [`bin/compile`](/).
-
-# The location of the pre-compiled cryptography binary.
-VENDORED_GDAL="${S3_BASE_URL}/${STACK}/libraries/vendor/gdal.tar.gz"
-VENDORED_GEOS="${S3_BASE_URL}/${STACK}/libraries/vendor/geos.tar.gz"
-VENDORED_PROJ="${S3_BASE_URL}/${STACK}/libraries/vendor/proj.tar.gz"
-
-PKG_CONFIG_PATH="/app/.heroku/vendor/lib/pkgconfig:$PKG_CONFIG_PATH"
-
-# Syntax sugar.
-# shellcheck source=bin/utils
-source "$BIN_DIR/utils"
-
-if [[ "$BUILD_WITH_GEO_LIBRARIES" && "${STACK}" == 'heroku-20' ]]; then
-  puts-warn "The GDAL, GEOS and PROJ binaries and BUILD_WITH_GEO_LIBRARIES functonality is not supported on Heroku-20."
-  puts-warn "Please use this buildpack for GDAL, GEOS and PROJ: https://github.com/heroku/heroku-geo-buildpack"
-  puts-warn "To hide this message, unset the BUILD_WITH_GEO_LIBRARIES variable using: heroku config:unset BUILD_WITH_GEO_LIBRARIES"
-elif [[ "$BUILD_WITH_GEO_LIBRARIES" ]]; then
-  mcount "buildvar.BUILD_WITH_GEO_LIBRARIES"
-
-  puts-warn "The GDAL, GEOS and PROJ binaries and BUILD_WITH_GEO_LIBRARIES functonality are now deprecated."
-  puts-warn "An alternative buildpack to enable GDAL, GEOS and PROJ use is available here - https://github.com/heroku/heroku-geo-buildpack"
-
-  if [ ! -f ".heroku/vendor/bin/proj" ]; then
-    echo "-----> Bootstrapping gdal, geos, proj."
-    mkdir -p .heroku/vendor
-    # Download and extract cryptography into target vendor directory.
-    curl "$VENDORED_GDAL" -s | tar zxv -C .heroku/vendor &> /dev/null
-    curl "$VENDORED_GEOS" -s | tar zxv -C .heroku/vendor &> /dev/null
-    curl "$VENDORED_PROJ" -s | tar zxv -C .heroku/vendor &> /dev/null
-
-    mcount "steps.vendor.geo_libs"
-    # Copy libjasper from build image to slug.
-    if [[ "$STACK" == "heroku-16" ]]; then
-      cp /usr/lib/x86_64-linux-gnu/libjasper.so* ".heroku/vendor/lib/."
-      mcount "steps.vendor.libjasper"
-    fi
-
-  fi
-
-  GDAL=$(pwd)/vendor
-  export GDAL
-  # set path for post_compile hooks
-  export GDAL_LIBRARY_PATH="$BUILD_DIR/.heroku/vendor/lib/libgdal.so"
-  export GEOS_LIBRARY_PATH="$BUILD_DIR/.heroku/vendor/lib/libgeos_c.so"
-  # set path for runtime environmeht
-  set_env GDAL_LIBRARY_PATH "/app/.heroku/vendor/lib/libgdal.so"
-  set_env GEOS_LIBRARY_PATH "/app/.heroku/vendor/lib/libgeos_c.so"
-fi
diff --git a/bin/warnings b/bin/warnings
index b987955d1..034d0dd1b 100755
--- a/bin/warnings
+++ b/bin/warnings
@@ -46,10 +46,36 @@ six-included() {
   fi
 }
 
+geo-gdal-support() {
+  if [[ -f "${ENV_DIR}/BUILD_WITH_GEO_LIBRARIES" ]]; then
+    mcount "warnings.BUILD_WITH_GEO_LIBRARIES"
+    echo
+    puts-warn "The Python buildpack's BUILD_WITH_GEO_LIBRARIES functonality is no longer supported:"
+    puts-warn "https://help.heroku.com/D5INLB1A/python-s-build_with_geo_libraries-legacy-feature-is-now-deprecated"
+    puts-warn
+    puts-warn "For GDAL, GEOS and PROJ support, use the Geo buildpack alongside the Python buildpack:"
+    puts-warn "https://github.com/heroku/heroku-geo-buildpack"
+    puts-warn
+    puts-warn "To hide this message, unset the BUILD_WITH_GEO_LIBRARIES variable using:"
+    puts-warn "heroku config:unset BUILD_WITH_GEO_LIBRARIES"
+    echo
+    return
+  fi
+  if grep -qi 'Could not find gdal-config' "$WARNINGS_LOG"; then
+    mcount 'warnings.gdal'
+    echo
+    puts-warn "Hello! Package installation failed since the GDAL library was not found."
+    puts-warn "For GDAL, GEOS and PROJ support, use the Geo buildpack alongside the Python buildpack:"
+    puts-warn "https://github.com/heroku/heroku-geo-buildpack"
+    puts-warn "  -- Much Love, Heroku."
+  fi
+}
+
 show-warnings() {
   old-platform
   scipy-included
   distribute-included
   six-included
+  geo-gdal-support
 }
 
diff --git a/builds/libraries/vendor/gdal b/builds/libraries/vendor/gdal
deleted file mode 100755
index 7cb110ea8..000000000
--- a/builds/libraries/vendor/gdal
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-# Build Path: /app/.heroku/vendor/
-
-OUT_PREFIX=$1
-
-# Use new path, containing autoconf.
-export PATH="/app/.heroku/python/bin/:$PATH"
-hash -r
-
-
-echo "Building gdal…"
-
-VERSION="2.2.1"
-SOURCE_TARBALL="http://download.osgeo.org/gdal/${VERSION}/gdal-${VERSION}.tar.gz"
-
-curl -L $SOURCE_TARBALL | tar zx
-
-pushd "gdal-${VERSION}"
-./configure --prefix=$OUT_PREFIX --enable-static=no  &&
-make
-make install
-
-# Cleanup
-popd
diff --git a/builds/libraries/vendor/geos b/builds/libraries/vendor/geos
deleted file mode 100755
index 3c7bcab27..000000000
--- a/builds/libraries/vendor/geos
+++ /dev/null
@@ -1,25 +0,0 @@
-#!/usr/bin/env bash
-# Build Path: /app/.heroku/vendor/
-
-OUT_PREFIX=$1
-
-# Use new path, containing autoconf.
-export PATH="/app/.heroku/python/bin/:$PATH"
-hash -r
-
-
-echo "Building geos…"
-
-VERSION=3.6.2
-
-SOURCE_TARBALL="http://download.osgeo.org/geos/geos-${VERSION}.tar.bz2"
-
-curl -L $SOURCE_TARBALL | tar xj
-
-pushd "geos-${VERSION}"
-./configure --prefix=$OUT_PREFIX --enable-static=no &&
-make
-make install
-
-# Cleanup
-popd
diff --git a/builds/libraries/vendor/proj b/builds/libraries/vendor/proj
deleted file mode 100755
index 7f11578bb..000000000
--- a/builds/libraries/vendor/proj
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-# Build Path: /app/.heroku/vendor/
-
-OUT_PREFIX=$1
-
-# Use new path, containing autoconf.
-export PATH="/app/.heroku/python/bin/:$PATH"
-hash -r
-
-
-echo "Building gdal…"
-
-VERSION=4.9.3
-SOURCE_TARBALL="http://download.osgeo.org/proj/proj-${VERSION}.tar.gz"
-
-curl -L $SOURCE_TARBALL | tar zx
-
-pushd "proj-${VERSION}"
-./configure --prefix=$OUT_PREFIX --enable-static=no
-make
-make install
-
-# Cleanup
-popd
diff --git a/test/fixtures/gdal/requirements.txt b/test/fixtures/gdal/requirements.txt
new file mode 100644
index 000000000..fe72cdd42
--- /dev/null
+++ b/test/fixtures/gdal/requirements.txt
@@ -0,0 +1 @@
+gdal
diff --git a/test/fixtures/geos/requirements.txt b/test/fixtures/geos/requirements.txt
deleted file mode 100644
index 68d357cf8..000000000
--- a/test/fixtures/geos/requirements.txt
+++ /dev/null
@@ -1 +0,0 @@
-django
\ No newline at end of file
diff --git a/test/run-deps b/test/run-deps
index 4af435f70..5db742753 100755
--- a/test/run-deps
+++ b/test/run-deps
@@ -17,18 +17,18 @@ testCollectstatic() {
   assertCaptured "collectstatic"
 }
 
-testGEOS() {
+testBuildWithGeoLibrariesWarning() {
   local env_dir="$(mktmpdir)"
   echo '1' > "${env_dir}/BUILD_WITH_GEO_LIBRARIES"
-  compile 'geos' '' "${env_dir}"
-  if [[ $STACK == "heroku-20" ]]; then
-    assertCaptured " !     The GDAL, GEOS and PROJ binaries and BUILD_WITH_GEO_LIBRARIES functonality is not supported on Heroku-20."
-  else
-    assertCaptured " !     The GDAL, GEOS and PROJ binaries and BUILD_WITH_GEO_LIBRARIES functonality are now deprecated."
-  fi
-  # This should assertCapturedError on Heroku-20, but the test doesn't actually
-  # install anything that uses GEOS so succeeds (see W-8145375)
-  assertCapturedSuccess
+  compile 'gdal' '' "${env_dir}"
+  assertCaptured " !     The Python buildpack's BUILD_WITH_GEO_LIBRARIES functonality is no longer supported"
+  assertCapturedError
+}
+
+testGDALWarning() {
+  compile 'gdal'
+  assertCaptured " !     Hello! Package installation failed since the GDAL library was not found."
+  assertCapturedError
 }
 
 testNLTK() {
diff --git a/test/run-features b/test/run-features
index d2e6a3cee..599940f3b 100755
--- a/test/run-features
+++ b/test/run-features
@@ -131,7 +131,6 @@ testHooks() {
     PROFILE_PATH
     PWD
     PYTHONUNBUFFERED
-    S3_BASE_URL
     SHLVL
     SOME_APP_CONFIG_VAR
     STACK