diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5075d24b..d3554a4b 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,13 +10,13 @@ jobs:
     strategy:
       matrix:
         # Python maintains 5 versions, along with the to-be-released version. Every October, this changes.
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', 'pypy-3.10']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14', 'pypy-3.10']
         os: [ macos-latest, ubuntu-latest, windows-latest ]
       fail-fast: false
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index b2f57593..da039fe3 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -10,11 +10,11 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', 'pypy-3.10']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14', 'pypy-3.10']
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Set up python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
 
@@ -34,7 +34,7 @@ jobs:
       matrix:
         python-version: [ '3.10' ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           submodules: true
 
@@ -84,7 +84,7 @@ jobs:
             cibw_arch: "i686 x86_64 aarch64"
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           submodules: true
 
@@ -106,8 +106,11 @@ jobs:
           # See the following for the status of python versions (ie. what's EoL'd, security only, etc):
           # https://devguide.python.org/versions/
           #
-          # At the time of writing, anything older than 3.9 is end-of-life.
-          CIBW_BUILD: "cp39-* cp310-* cp311-* cp312-* cp313-*"
+          # At the time of writing, anything older than 3.10 is end-of-life. (3.9 has no build
+          # for the Ubuntu 26.04 runners that ubuntu-latest now resolves to.)
+          # 3.15 is excluded until jsonconversion works with it: it calls the private
+          # json.encoder._make_iterencode with an isinstance= kwarg that 3.15 removed.
+          CIBW_BUILD: "cp310-* cp311-* cp312-* cp313-* cp314-*"
           CIBW_ARCHS: ${{ matrix.cibw_arch }}
           CIBW_ARCHS_LINUX: ${{ matrix.cibw_arch }}
 
diff --git a/README.md b/README.md
index 90fc29bd..649d6519 100644
--- a/README.md
+++ b/README.md
@@ -86,13 +86,13 @@ installed Python.
 Install relevant versions of Python:
 
 ```
-$ for V in 3.8.10 3.9.5 do pyenv install $V; done
+$ for V in 3.10.19 3.14.10; do pyenv install $V; done
 ```
 
 Once you have these installations, add them as a local `pyenv` configuration
 
 ```
-$ pyenv local 3.8.10 3.9.5
+$ pyenv local 3.10.19 3.14.10
 ```
 
 Assuming you have `pyenv` properly set up (making sure `pyenv init` is evaluated into your shell),
@@ -102,14 +102,14 @@ you can now run `tox`:
 # Run tox for all versions of python which executes py.test.
 $ tox
 
-# Run tox for just Python 3.8 and 3.9.
-$ tox -e py38,py39
+# Run tox for just Python 3.10 and 3.14.
+$ tox -e py310,py314
 
 # Run tox for a specific version and run py.test with high verbosity
-$ tox -e py39 -- py.test -vv
+$ tox -e py310 -- py.test -vv
 
 # Run tox for a specific version and just the virtual env REPL.
-$ tox -e py39 -- python
+$ tox -e py310 -- python
 ```
 
 ## TODO
diff --git a/pyproject.toml b/pyproject.toml
index 7cb34c5c..3e66eaa1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [project]
 name = "amazon-ion"
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 license = { "file" = "LICENSE" }
 authors = [{ "name" = "Amazon Ion Team", "email" = "ion-team@amazon.com" }]
 keywords = []
@@ -73,7 +73,7 @@ testpaths = ["tests"]
 #  running our default unit tests (minus benchmarking related tests). This ensures that we
 #  can easily test against supported python versions.
 [tool.tox]
-envlist = ["py3.9", "pypy3"] # default environments to run.
+envlist = ["py3.10", "pypy3"] # default environments to run.
 
 [tool.tox.env_run_base]
 extras = ["test"]